Signalling of general constrains flag

ABSTRACT

Methods, systems, apparatus for video processing are described. The processing may include encoding, decoding or transcoding. One example video processing method includes performing a conversion between a video and a bitstream of the video according to a rule, and wherein the rule specifies that a syntax element is included in a profile, tier, level information syntax structure to indicate whether one or more general constraint information syntax elements are included in a general constraint information syntax structure and/or whether the general constraint information syntax structure is included in the profile, tier, level information syntax structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent Application No. PCT/CN2021/095386, filed on May 24, 2021, which claims the priority to and benefits of International Patent Application No. PCT/CN2020/091740, filed on May 22, 2020. All the aforementioned patent applications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

This patent document relates to image and video coding and decoding.

BACKGROUND

Digital video accounts for the largest bandwidth use on the internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, it is expected that the bandwidth demand for digital video usage will continue to grow.

SUMMARY

The present document discloses techniques that can be used by video encoders and decoders for processing coded representation of video using control information useful for decoding of the coded representation.

In one example aspect, a video processing method is disclosed. The method includes performing a conversion between a video and a bitstream of the video according to a rule, and wherein the rule specifies that a syntax element is included in a profile, tier, level information syntax structure to indicate whether one or more general constraint information syntax elements are included in a general constraint information syntax structure and/or whether the general constraint information syntax structure is included in the profile, tier, level information syntax structure.

In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video and a bitstream of the video according to a rule, wherein a syntax structure includes information of one or more video coding layers that are included in the bitstream and correspond to one or more output layer sets; and wherein the rule specifies that a starting position of a syntax element in the syntax structure that specifies a level information to which the one or more output layer sets conform is constrained to align to a byte boundary.

In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that a syntax structure indicates constraint information about the bitstream; wherein the rule specifies that the syntax structure is allowed to include a syntax element without aligning to a byte boundary.

In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies where and how reserved bits are included in a syntax structure that indicates one or more coding constraints applicable to the conversion.

In another example aspect, another video processing method is disclosed. The method includes determining, for a conversion between a video comprising one or more pictures comprising one or more slices and a bitstream of the video, that only I slices are enabled for the conversion according to a rule; and performing the conversion according to the determining, wherein the rule specifies that, responsive to only I slices being enabled, the bitstream conforms to one or more additional constraints.

In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that one or more syntax elements in a sequence parameter set, a picture parameter set, a picture header, or a sequence header are constrained according to a general constraint information syntax element that indicates a constraint applicable to the conversion.

In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that whether or how a first syntax element in a syntax structure that indicates one or more constraints applicable to the conversion is indicated is dependent on whether or how a second syntax element is indicated in the syntax structure.

In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies whether or how a syntax element indicative of general constraints on the conversion is included in the bitstream depends on a profile and/or a level used for the conversion.

In yet another example aspect, a video encoder apparatus is disclosed. The video encoder comprises a processor configured to implement above-described methods.

In yet another example aspect, a video decoder apparatus is disclosed. The video decoder comprises a processor configured to implement above-described methods.

In yet another example aspect, a computer readable medium having code stored thereon is disclose. The code embodies one of the methods described herein in the form of processor-executable code.

These, and other, features are described throughout the present document.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of an example video processing system.

FIG. 2 is a block diagram of a video processing apparatus.

FIG. 3 is a flowchart for an example method of video processing.

FIG. 4 is a block diagram that illustrates a video coding system in accordance with some embodiments of the disclosed technology.

FIG. 5 is a block diagram that illustrates an encoder in accordance with some embodiments of the disclosed technology.

FIG. 6 is a block diagram that illustrates a decoder in accordance with some embodiments of the disclosed technology.

FIG. 7 is a flowchart for an example method of video processing based on some implementations of the disclosed technology.

FIGS. 8A and 8B are flowcharts for example methods of video processing based on some implementations of the disclosed technology.

FIGS. 9A to 9E are flowcharts for example methods of video processing based on some implementations of the disclosed technology.

DETAILED DESCRIPTION

Section headings are used in the present document for ease of understanding and do not limit the applicability of techniques and embodiments disclosed in each section only to that section. Furthermore, H.266 terminology is used in some description only for ease of understanding and not for limiting scope of the disclosed techniques. As such, the techniques described herein are applicable to other video codec protocols and designs also.

1. Introduction

This document is related to video coding technologies. Specifically, it is about the design of constraint flags related syntax in video coding. The ideas may be applied individually or in various combination, to any video coding standard or non-standard video codec that supports multi-layer video coding, e.g., the being-developed Versatile Video Coding (VVC).

2. Abbreviations

APS Adaptation Parameter Set

AU Access Unit

AUD Access Unit Delimiter

AVC Advanced Video Coding

CLVS Coded Layer Video Sequence

CPB Coded Picture Buffer

CRA Clean Random Access

CTU Coding Tree Unit

CVS Coded Video Sequence

DPB Decoded Picture Buffer

DPS Decoding Parameter Set

EOB End Of Bitstream

EOS End Of Sequence

GDR Gradual Decoding Refresh

HEVC High Efficiency Video Coding

HRD Hypothetical Reference Decoder

IDR Instantaneous Decoding Refresh

JEM Joint Exploration Model

MCTS Motion-Constrained Tile Sets

NAL Network Abstraction Layer

OLS Output Layer Set

PH Picture Header

PPS Picture Parameter Set

PTL Profile, Tier and Level

PU Picture Unit

RBSP Raw Byte Sequence Payload

SEI Supplemental Enhancement Information

SH Slice Header

SPS Sequence Parameter Set

SVC Scalable Video Coding

VCL Video Coding Layer

VPS Video Parameter Set

VTM VVC Test Model

VUI Video Usability Information

VVC Versatile Video Coding

3. Background

Video coding standards have evolved primarily through the development of the well-known ITU-T and ISO/IEC standards. The ITU-T produced H.261 and H.263, ISO/IEC produced MPEG-1 and MPEG-4 Visual, and the two organizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4 Advanced Video Coding (AVC) and H.265/HEVC standards. Since H.262, the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized. To explore the future video coding technologies beyond HEVC, the Joint Video Exploration Team (JVET) was founded by VCEG and MPEG jointly in 2015. Since then, many new methods have been adopted by JVET and put into the reference software named Joint Exploration Model (JEM). The JVET meeting is concurrently held once every quarter, and the new coding standard is targeting at 50% bitrate reduction as compared to HEVC. The new video coding standard was officially named as Versatile Video Coding (VVC) in the April 2018 JVET meeting, and the first version of VVC test model (VTM) was released at that time. As there are continuous effort contributing to VVC standardization, new coding techniques are being adopted to the VVC standard in every JVET meeting. The VVC working draft and test model VTM are then updated after every meeting. The VVC project is now aiming for technical completion (FDIS) at the July 2020 meeting.

3.1. General Profile, Tier, Level Syntax and Semantics

In the latest VVC draft text, the general profile, tier, level syntax and semantics are as follows:

Descriptor profile_tier_level( profileTierPresentFlag, max_NumSubLayersMinus1 ) {  if( profileTierPresentFlag ) {   general_profile_idc u(7)   general_tier_flag u(1)   general_constraint_info( )  }  general_level_idc u(8)  if( profileTierPresentFlag ) {   num_sub_profiles u(8)   for( i = 0; i < num_sub_profiles; i++ )    general_sub_profile_idc[ i ] u(32)  }  for( i = 0; i < max_NumSubLayersMinus1; i++ )   sublayer_level_present_flag[ i ] u(1)  while( !byte_aligned( ) )   ptl_alignment_zero_bit f(1)  for( i = 0; i < maxNumSubLayersMinus1; i++ )   if( sublayer_level_present_flag[ i ] )    sublayer_level_idc[ i ] u(8) } A profile_tier_level( ) syntax structure provides level information and, optionally, profile, tier, sub-profile, and general constraints information. When the profile_tier_level( ) syntax structure is included in a VPS, the OlsInScope is one or more OLSs specified by the VPS. When the profile_tier_level( ) syntax structure is included in an SPS, the OlsInScope is the OLS that includes only the layer that is the lowest layer among the layers that refer to the SPS, and this lowest layer is an independent layer. general_profile_idc indicates a profile to which OlsInScope conforms as specified in Annex A. Bitstreams shall not contain values of general_profile_idc other than those specified in Annex A. Other values of general_profile_idc are reserved for future use by ITU-T|ISO/IEC. general_tier_flag specifies the tier context for the interpretation of general_level_idc as specified in Annex A. general_level_idc indicates a level to which OlsInScope conforms as specified in Annex A. Bitstreams shall not contain values of general_level_idc other than those specified in Annex A. Other values of general_level_idc are reserved for future use by TTU-T|ISO/IEC.

-   -   NOTE 1—A greater value of general_level_idc indicates a higher         level. The maximum level signalled in the DCI NAL unit for         OlsInScope may be higher than but cannot be lower than the level         signalled in the SPS for a CLVS contained within OlsInScope.     -   NOTE 2—When OlsInScope conforms to multiple profiles,         general_profile_idc should indicate the profile that provides         the preferred decoded result or the preferred bitstream         identification, as determined by the encoder (in a manner not         specified in this Specification).     -   NOTE 3—When the CVSs of OlsInScope conform to different         profiles, multiple profile_tier_level( ) syntax structures may         be included in the DCI NAL unit such that for each CVS of the         OlsInScope there is at least one set of indicated profile, tier,         and level for a decoder that is capable of decoding the CVS.         num_sub_profiles specifies the number of the         general_sub_profile_idc[i] syntax elements.         general_sub_profile_idc[i] indicates the i-th interoperability         metadata registered as specified by Rec. ITU-T T.35, the         contents of which are not specified in this Specification.         sublayer_level_present_flag[i] equal to 1 specifies that level         information is present in the profile_tier_level( ) syntax         structure for the sublayer representation with TemporalId equal         to i. sublayer_level_present_flag[i] equal to 0 specifies that         level information is not present in the profile_tier_level( )         syntax structure for the sublayer representation with TemporalId         equal to i.         ptl_alignment_zero_bits shall be equal to 0.         The semantics of the syntax element sublayer_level_idc[i] is,         apart from the specification of the inference of not present         values, the same as the syntax element general_level_idc, but         apply to the sublayer representation with TemporalId equal to i.         When not present, the value of sublayer_level_idc[i] is inferred         as follows:     -   sublayer_level_idc[maxNumSubLayersMinus1] is inferred to be         equal to general_level_idc of the same profile_tier_level( )         structure,     -   For i from maxNumSubLayersMinus1−1 to 0 (in decreasing order of         values of i), inclusive, sublayer_level_idc[i] is inferred to be         equal to sublayer_level_idc[i+1].

3.2. General Constraint Information Syntax and Semantics

In the latest VVC draft text, the general constraint information syntax and semantics are as follows.

Descriptor general_constraint_info( ) {  general_progressive_source_flag u(1)  general_interlaced_source_flag u(1)  general_non_packed_constraint_flag u(1)  general_frame_only_constraint_flag u(1)  general_non_projected_constraint_flag u(1)  intra_only_constraint_flag u(1)  max_bitdepth_constraint_idc u(4)  max_chroma_format_constraint_idc u(2)  no_res_change_in_clvs_constraint_flag u(1)  one_tile_per_pic_constraint_flag u(1)  one_slice_per_pic_constraint_flag u(1)  one_subpic_per_pic_constraint_flag u(1)  no_qtbtt_dual_tree_intra_constraint_flag u(1)  no_partition_constraints_override_constraint_flag u(1)  no_sao_constraint_flag u(1)  no_alf_constraint_flag u(1)  no_ccalf_constraint_flag u(1)  no_joint_cbcr_constraint_flag u(1)  no_ref_wraparound_constraint_flag u(1)  no_temporal_mvp_constraint_flag u(1)  no_sbtmvp_constraint_flag u(1)  no_amvr_constraint_flag u(1)  no_bdof_constraint_flag u(1)  no_dmvr_constraint_flag u(1)  no_cclm_constraint_flag u(1)  no_mts_constraint_flag u(1)  no_sbt_constraint_flag u(1)  no_affine_motion_constraint_flag u(1)  no_bcw_constraint_flag u(1)  no_ibc_constraint_flag u(1)  no_ciip_constraint_flag u(1)  no_fpel_mmvd_constraint_flag u(1)  no_gpm_constraint_flag u(1)  no_ladf_constraint_flag u(1)  no_transform_skip_constraint_flag u(1)  no_bdpcm_constraint_flag u(1)  no_qp_delta_constraint_flag u(1)  no_dep_quant_constraint_flag u(1)  no_sign_data_hiding_constraint_flag u(1)  no_mixed_nalu_types_in_pic_constraint_flag u(1)  no_trail_constraint_flag u(1)  no_stsa_constraint_flag u(1)  no_rasl_constraint_flag u(1)  no_radl_constraint_flag u(1)  no_idr_constraint_flag u(1)  no_cra_constraint_flag u(1)  no_gdr_constraint_flag u(1)  no_aps_constraint_flag u(1)  while( !byte_aligned( ) )   gci_alignment_zero_bit f(1)  num_reserved_constraint_bytes u(8)  for( i = 0; i < num_reserved_constraint_bytes; i++ )   gci_reserved_constraint_byte[ i ] u(8) } general_progressive_source_flag and general_interlaced_source_flag are interpreted as follows:

-   -   If general_progressive_source_flag is equal to 1 and         general_interlaced_source_flag is equal to 0, the source scan         type of the pictures in OlsInScope should be interpreted as         progressive only.     -   Otherwise, if general_progressive_source_flag is equal to 0 and         general_interlaced_source_flag is equal to 1, the source scan         type of the pictures in OlsInScope should be interpreted as         interlaced only.     -   Otherwise, if general_progressive_source_flag is equal to 0 and         general_interlaced_source_flag is equal to 0, the source scan         type of the pictures in OlsInScope should be interpreted as         unknown or unspecified.     -   Otherwise (general_progressive_source_flag is equal to 1 and         general_interlaced_source_flag is equal to 1), the source scan         type of each picture in OlsInScope is indicated at the picture         level using the syntax element source_scan_type in a frame-field         information SEI message. It is a requirement of bitstream         conformance that when general_progressive_source_flag is equal         to 1 and general_interlaced_source_flag is equal to 1, a         frame-field information SEI message shall be present in each AU.     -   NOTE 1—Decoders may ignore the values of         general_progressive_source_flag and         general_interlaced_source_flag. Moreover, the actual source scan         type of the pictures is outside the scope of this Specification         and the method by which the encoder selects the values of         general_progressive_source_flag and         general_interlaced_source_flag is unspecified.         general_non_packed_constraint_flag equal to 1 specifies that         there shall not be any frame packing arrangement SEI messages         present in the bitstream of the OlsInScope.         general_non_packed_constraint_flag equal to 0 does not impose         such a constraint.     -   NOTE 2—Decoders may ignore the value of         general_non_packed_constraint_flag, as there are no decoding         process requirements associated with the presence or         interpretation of frame packing arrangement SEI messages.         general_frame_only_constraint_flag equal to 1 specifies that         OlsInScope conveys pictures that represent frames.         general_frame_only_constraint_flag equal to 0 specifies that         OlsInScope conveys pictures that may or may not represent         frames.     -   NOTE 3—Decoders may ignore the value of         general_frame_only_constraint_flag, as there are no decoding         process requirements associated with it.         general_non_projected_constraint_flag equal to 1 specifies that         there shall not be any equirectangular projection SEI messages         or generalized cubemap projection SEI messages present in the         bitstream of the OlsInScope.         general_non_projected_constraint_flag equal to 0 does not impose         such a constraint.     -   NOTE 4—Decoders may ignore the value of         general_non_projected_constraint_flag, as there are no decoding         process requirements associated with the presence or         interpretation of equirectangular projection SEI messages and         generalized cubemap projection SEI messages.         intra_only_constraint_flag equal to 1 specifies that slice_type         shall be equal to 1. intra_only_constraint_flag equal to 0 does         not impose such a constraint.         max_bitdepth_constraint_idc specifies that bit_depth_minus8         shall be in the range of 0 to max_bitdepth_constraint_idc,         inclusive.         max_chroma_format_constraint_idc specifies that         chroma_format_idc shall be in the range of 0 to         max_chroma_format_constraint_idc, inclusive.         no_res_change_in_clvs_constraint_flag equal to 1 specifies that         res_change_in_clvs_allowed_flag shall be equal to 0.         no_res_change_in_clvs_constraint_flag equal to 0 does not impose         such a constraint.         one_tile_per_pic_constraint_flag equal to 1 specifies that each         picture shall contain only one tile.         one_tile_per_pic_constraint_flag equal to 0 does not impose such         a constraint.         one_slice_per_pic_constraint_flag equal to 1 specifies that each         picture shall contain only one slice.         one_slice_per_pic_constraint_flag equal to 0 does not impose         such a constraint.         one_subpic_per_pic_constraint_flag equal to 1 specifies that         each picture shall contain only one subpicture.         one_subpic_per_pic_constraint_flag equal to 0 does not impose         such a constraint. When one_slice_per_pic_constraint_flag is         equal to 1, the value of one_subpic_per_pic_constraint_flag         shall be equal to 1.         no_gtbtt_dual_tree_intra_constraint_flag equal to 1 specifies         that gtbtt_dual_tree_intra_flag shall be equal to 0.         no_gtbtt_dual_tree_intra_constraint_flag equal to 0 does not         impose such a constraint.         no_partition_constraints_override_constraint_flag equal to 1         specifies that partition_constraints_override_enabled_flag shall         be equal to 0. no_partition_constraints_override_constraint_flag         equal to 0 does not impose such a constraint.         no_sao_constraint_flag equal to 1 specifies that         sps_sao_enabled_flag shall be equal to 0. no_sao_constraint_flag         equal to 0 does not impose such a constraint.         no_alf_constraint_flag equal to 1 specifies that         sps_alf_enabled_flag shall be equal to 0. no_alf_constraint_flag         equal to 0 does not impose such a constraint.         no_ccalf_constraint_flag equal to 1 specifies that         sps_ccalf_enabled_flag shall be equal to 0.         no_ccalf_constraint_flag equal to 0 does not impose such a         constraint.         no_joint_cbcr_constraint_flag equal to 1 specifies that         sps_joint_cbcr_enabled_flag shall be equal to 0.         no_joint_cbcr_constraint_flag equal to 0 does not impose such a         constraint.         no_ref_wraparound_constraint_flag equal to 1 specifies that         sps_ref_wraparound_enabled_flag shall be equal to 0.         no_ref_wraparound_constraint_flag equal to 0 does not impose         such a constraint.         no_temporal_mvp_constraint_flag equal to 1 specifies that         sps_temporal_mvp_enabled_flag shall be equal to 0.         no_temporal_mvp_constraint_flag equal to 0 does not impose such         a constraint.         no_sbtmvp_constraint_flag equal to 1 specifies that         sps_sbtmvp_enabled_flag shall be equal to 0.         no_sbtmvp_constraint_flag equal to 0 does not impose such a         constraint.         no_amvr_constraint_flag equal to 1 specifies that         sps_amvr_enabled_flag shall be equal to 0.         no_amvr_constraint_flag equal to 0 does not impose such a         constraint.         no_bdof_constraint_flag equal to 1 specifies that         sps_bdof_enabled_flag shall be equal to 0.         no_bdof_constraint_flag equal to 0 does not impose such a         constraint.         no_dmvr_constraint_flag equal to 1 specifies that         sps_dmvr_enabled_flag shall be equal to 0.         no_dmvr_constraint_flag equal to 0 does not impose such a         constraint.         no_cclm_constraint_flag equal to 1 specifies that         sps_cclm_enabled_flag shall be equal to 0.         no_cclm_constraint_flag equal to 0 does not impose such a         constraint.         no_mts_constraint_flag equal to 1 specifies that         sps_mts_enabled_flag shall be equal to 0. no_mts_constraint_flag         equal to 0 does not impose such a constraint.         no_sbt_constraint_flag equal to 1 specifies that         sps_sbt_enabled_flag shall be equal to 0. no_sbt_constraint_flag         equal to 0 does not impose such a constraint.         no_affine_motion_constraint_flag equal to 1 specifies that         sps_affine_enabled_flag shall be equal to 0.         no_affine_motion_constraint_flag equal to 0 does not impose such         a constraint.         no_bcw_constraint_flag equal to 1 specifies that         sps_bcw_enabled_flag shall be equal to 0. no_bcw_constraint_flag         equal to 0 does not impose such a constraint.         no_ibc_constraint_flag equal to 1 specifies that         sps_ibc_enabled_flag shall be equal to 0. no_ibc_constraint_flag         equal to 0 does not impose such a constraint.         no_ciip_constraint_flag equal to 1 specifies that         sps_ciip_enabled_flag shall be equal to 0.         no_cipp_constraint_flag equal to 0 does not impose such a         constraint.         no_fpel_mmvd_constraint_flag equal to 1 specifies that         sps_fpel_mmvd_enabled_flag shall be equal to 0.         no_fpel_mmvd_constraint_flag equal to 0 does not impose such a         constraint.         no_gpm_constraint_flag equal to 1 specifies that         sps_gpm_enabled_flag shall be equal to 0. no_gpm_constraint_flag         equal to 0 does not impose such a constraint.         no_ladf_constraint_flag equal to 1 specifies that         sps_ladf_enabled_flag shall be equal to 0.         no_ladf_constraint_flag equal to 0 does not impose such a         constraint.         no_transform_skip_constraint_flag equal to 1 specifies that         sps_transform_skip_enabled_flag shall be equal to 0.         no_transform_skip_constraint_flag equal to 0 does not impose         such a constraint.         no_bdpcm_constraint_flag equal to 1 specifies that         sps_bdpcm_enabled_flag shall be equal to 0.         no_bdpcm_constraint_flag equal to 0 does not impose such a         constraint.         no_qp_delta_constraint_flag equal to 1 specifies that it is a         requirement of bitstream conformance that         cu_qp_delta_enabled_flag shall be equal to 0.         no_qp_delta_constraint_flag equal to 0 does not impose such a         constraint.         no_dep_quant_constraint_flag equal to 1 specifies that it is a         requirement of bitstream conformance that         sps_dep_quant_enabled_flag shall be equal to 0.         no_dep_quant_constraint_flag equal to 0 does not impose such a         constraint.         no_sign_data_hiding_constraint_flag equal to 1 specifies that it         is a requirement of bitstream conformance that         sps_sign_data_hiding_enabled_flag shall be equal to 0.         no_sign_data_hiding_constraint_flag equal to 0 does not impose         such a constraint.         no_mixed_nalu_types_in_pic_constraint_flag equal to 1 specifies         that it is a requirement of bitstream conformance that         mixed_nalu_types_in_pic_flag shall be equal to 0.         no_mixed_nalu_types_in_pic_constraint_flag equal to 0 does not         impose such a constraint.         no_trail_constraint_flag equal to 1 specifies that there shall         be no NAL unit with nuh_unit_type equal to TRAIL_NUT present in         OlsInScope. no_trail_constraint_flag equal to 0 does not impose         such a constraint.         no_stsa_constraint_flag equal to 1 specifies that there shall be         no NAL unit with nuh_unit_type equal to STSA_NUT present in         OlsInScope. no_stsa_constraint_flag equal to 0 does not impose         such a constraint.         no_rasl_constraint_flag equal to 1 specifies that there shall be         no NAL unit with nuh_unit_type equal to RASL_NUT present in         OlsInScope. no_rasl_constraint_flag equal to 0 does not impose         such a constraint.         no_radl_constraint_flag equal to 1 specifies that there shall be         no NAL unit with nuh_unit_type equal to RADL_NUT present in         OlsInScope. no_radl_constraint_flag equal to 0 does not impose         such a constraint.         no_idr_constraint_flag equal to 1 specifies that there shall be         no NAL unit with nuh_unit_type equal to IDR_W_RADL or IDR_N_LP         present in OlsInScope. no_idr_constraint_flag equal to 0 does         not impose such a constraint.         no_cra_constraint_flag equal to 1 specifies that there stall be         no NAL unit with nuh_unit_type equal to CRA NUT present in         OlsInScope. no_cra_constraint_flag equal to 0 does not impose         such a constraint.         no_gdr_constraint_flag equal to 1 specifies that there shall be         no NAL unit with nuh_unit_type equal to GDR_NUT present in         OlsInScope. no_gdr_constraint_flag equal to 0 does not impose         such a constraint.         no_aps_constraint_flag equal to 1 specifies that there shall be         no NAL unit with nuh_unit_type equal to PREFIX_APS_NUT or         SUFFIX_APS_NUT present in OlsInScope. no_aps_constraint_flag         equal to 0 does not impose such a constraint.         gci_alignment_zero_bits shall be equal to 0.         num_reserved_constraint_bytes specifies the number of the         reserved constraint bytes. The value of         num_reserved_constraint_bytes shall be 0. Other values of         num_reserved_constraint_bytes are reserved for future use by         ITU-T|ISO/IEC and shall not be present in bitstreams conforming         to this version of this Specification.         gci_reserved_constraint_byte[i] may have any value. Its presence         and value do not affect decoder conformance to profiles         specified in this version of this Specification. Decoders         conforming to this version of this Specification shall ignore         the values of all the gci_reserved_constraint_byte[i] syntax         elements.

3.3. DCI Syntax and Semantics

In the latest VVC draft text, the DCI syntax and semantics are as follows:

Descriptor decoding_capability_information_rbsp( ) {  dci_max_sublayers_minus1 u(3)  dci_reserved_zero_bit u(1)  dci_num_ptls_minus1 u(4)  for( i = 0; i <= dci_num_ptls_minus1; i++ )   profile_tier_level( 1, 0 )  dci_extension_flag u(1)  if( dci_extension_flag )   while( more_rbsp_data( ) )    dci_extension_data_flag u(1)  rbsp_trailing_bits( ) } A DCI RBSP may be made available to the decoder, through either being present in the bitstream, included in at least the first AU of the bitstream, or provided through external means.

-   -   NOTE 1—The information contained in the DCI RBSP is not         necessary for operation of the decoding process specified in         clauses 2 through 9 of this Specification.         When present, all DCI NAL units in a bitstream shall have the         same content.         dci_max_sublayers_minus1 plus 1 specifies the maximum number of         temporal sublayers that may be present in a layer in each CVS of         the bitstream. The value of dci_max_sublayers_minus1 shall be in         the range of 0 to 6, inclusive.         dci_reserved_zero_bit shall be equal to 0 in bitstreams         conforming to this version of this Specification. The value 1         for dci_reserved_zero_bit is reserved for future use by         ITU-T|ISO/IEC.         dci_num_ptls_minus1 plus 1 specifies the number of         profile_tier_level( ) syntax structures in the DCI NAL unit.         It is a requirement of bitstream conformance that each OLS in a         CVS in the bitstream shall conforms to at least one of the         profile_tier_level( ) syntax structures in the DCI NAL unit.     -   NOTE 2—The DCI NAL unit may include PTL information, possibly         carved in multiple profile_tier_level( ) syntax structures, that         applies collectively to multiple OLSs, and does not need to         include PTL information for each of the OLSs individually.         dci_extension_flag equal to 0 specifies that no         dci_extension_data_flag syntax elements are present in the DCI         RBSP syntax structure. dci_extension_flag equal to 1 specifies         that there are dci_extension_data_flag syntax elements present         in the DCI RBSP syntax stricture.         dci_extension_data_flag may have any value. Its presence and         value do not affect decoder conformance to profiles specified in         Annex A. Decoders conforming to this version of this         Specification shall ignore all dci_extension_data_flag syntax         elements.

3.4. VPS Syntax and Semantics

In the latest VVC draft text, the VPS syntax and semantics are as follows:

Descriptor video_parameter_set_rbsp( ) {  vps_video_parameter_set_id u(4)  vps_max_layers_minus1 u(6)  vps_max_sublayers_minus1 u(3)  if( vps_max_layers_minus1 > 0 &&  vps_max_sublayers_minus1 > 0 )   vps_all_layers_same_num_sublayers_flag u(1)  if( vps_max_layers_minus1 > 0 )   vps_all_independent_layers_flag u(1)  for( i = 0; i <= vps_max_layers_minus1; i++ ) {   vps_layer_id[ i ] u(6)   if( i > 0 && !vps_all_independent_layers_flag ) {    vps_independent_layer_flag[ i ] u(1)    if( !vps_independent_layer_flag[ i ] ) {     for( j = 0; j < i; j++ )      vps_direct_ref_layer_flag[ i ][ j ] u(1)     max_tid_ref_present_flag[ i ] u(1)     if( max_tid_ref_present_flag[ i ] )      max_tid_il_ref_pics_plus1[ i ] u(3)    }   }  }  if( vps_max_layers_minus1 > 0 ) {   if( vps_all_independent_layers_flag )    each_layer_is_an_ols_flag u(1)   if( !each_layer_is_an_ols_flag ) {    if( !vps_all_independent_layers_flag )     ols_mode_idc u(2)    if( ols_mode_idc = = 2 ) {     num_output_layer_sets_minus1 u(8)     for( i = 1; i <=     num_output_layer_sets_minus1; i ++)      for( j = 0; j <= vps_max_layers_minus1; j++ )       ols_output_layer_flag[ i ][ j ] u(1)    }   }  }  vps_num_ptls_minus1 u(8)  for( i = 0; i <= vps_num_ptls_minus1; i++ ) {   if( i > 0 )    pt_present_flag[ i ] u(1)   if( vps_max_sublayers_minus1 > 0 &&   !vps_all_layers_same_num_sublayers_flag )    ptl_max_temporal_id[ i ] u(3)  }  while( !byte_aligned( ) )   vps_ptl_alignment_zero_bit /* equal to 0 */ f(1)  for( i = 0; i <= vps_num_ptls_minus1; i++ )   profile_tier_level( pt_present_flag[ i ],   ptl_max_temporal_id[ i ] )  for( i = 0; i < TotalNumOlss; i++ )   if( vps_num_ptls_minus1 > 0 )    ols_ptl_idx[ i ] u(8)  if( !vps_all_independent_layers_flag )   vps_num_dpb_params ue(v)  if( vps_num_dpb_params > 0 &&  vps_max_sublayers_minus1 > 0 )   vps_sublayer_dpb_params_present_flag u(1)  for( i = 0; i < vps_num_dpb_params; i++ ) {   if( vps_max_sublayers_minus1 > 0 &&   !vps_all_layers_same_num_sublayers_flag )    dpb_max_temporal_id[ i ] u(3)   dpb_parameters( dpb_max_temporal_id[ i ],   vps_sublayer_dpb_params_present_flag )  }  for( i = 0; i < TotalNumOlss; i++ ) {   if( NumLayersInOls[ i ] > 1 ) {    ols_dpb_pic_width[ i ] ue(v)    ols_dpb_pic_height[ i ] ue(v)    if( vps_num_dpb_params > 1 )     ols_dpb_params_idx[ i ] ue(v)   }  }  if( !each_layer_is_an_ols_flag )   vps_general_hrd_params_present_flag u(1)  if( vps_general_hrd_params_present_flag ) {   general_hrd_parameters( )   if( vps_max_sublayers_minus1 > 0 )    vps_sublayer_cpb_params_present_flag u(1)   num_ols_hrd_params_minus1 ue(v)   for( i = 0; i <= num_ols_hrd_params_minus1; i++ ) {    if( vps_max_sublayers_minus1 > 0 &&    !vps_all_layers_same_num_sublayers_flag )     hrd_max_tid[ i ] u(3)    firstSubLayer =    vps_sublayer_cpb_params_present_flag ? 0 :    hrd_max_tid[ i ]    ols_hrd_parameters( firstSubLayer,    hrd_max_tid[ i ] )   }   if( num_ols_hrd_params_minus1 + 1 !=     TotalNumOlss &&     num_ols_hrd_params_minus1 > 0 )    for( i = 1; i < TotalNumOlss; i++ )     if( NumLayersInOls[ i ] > 1 )      ols_hrd_idx[ i ] ue(v)  }  vps_extension_flag u(1)  if( vps_extension_flag )   while( more_rbsp_data( ) )    vps_extension_data_flag u(1)  rbsp_trailing_bits( ) } A VPS RBSP shall be available to the decoding process prior to it being referenced, included in at least one AU with TemporalId equal to 0 or provided through external means. All VPS NAL units with a particular value of vps_video_parameter_set_id in a CVS shall have the same content. vps_video_parameter_set_id provides an identifier for the VPS for reference by other syntax elements. The value of vps_video_parameter_set_id shall be greater than 0. vps_max_layers_minus1 plus 1 specifies the maximum allowed number of layers in each CVS referring to the VPS. vps_max_sublayers_minus1 plus 1 specifies the maximum number of temporal sublayers that may be present in a layer in each CVS referring to the VPS. The value of vps_max_sublayers_minus1 shall be in the range of 0 to 6, inclusive. vps_all_layers_same_num_sublayers_flag equal to 1 specifies that the number of temporal sublayers is the same for all the layers in each CVS referring to the VPS. vps_all_layers_same_num_sublayers_flag equal to 0 specifies that the layers in each CVS referring to the VPS may or may not have the same number of temporal sublayers. When not present, the value of vps_all_layers_same_num_sublayers_flag is inferred to be equal to 1. vps_all_independent_layers_flag equal to 1 specifies that all layers in the CVS are independently coded without using inter-layer prediction vps_all_independent_layers_flag equal to 0 specifies that one or more of the layers in the CVS may use inter-layer prediction. When not present, the value of vps_all_independent_layers_flag is inferred to be equal to 1. vps_layer_id[i] specifies the nuh_layer_id value of the i-th layer. For any two non-negative integer values of m and n, when m is less than n, the value of vps_layer_id[m] shall be less than vps_layer_id[n]. vps_independent_layer_flag[i] equal to 1 specifies that the layer with index i does not use inter-layer prediction. vps_independent_layer_flag[i] equal to 0 specifies that the layer with index i may use inter-layer prediction and the syntax elements vps_direct_ref_layer_flag[i][j] for j in the range of 0 to i−1, inclusive, are present in VPS. When not present, the value of vps_independent_layer_flag[i] is inferred to be equal to 1. vps_direct_ref_layer_flag[i][j] equal to 0 specifies that the layer with index j is not a direct reference layer for the layer with index i. vps_direct_ref_layer_flag[i][j] equal to 1 specifies that the layer with index j is a direct reference layer for the layer with index i. When vps_direct_ref_layer_flag[i][j] is not present for i and j in the range of 0 to vps_max_layers_minus1, inclusive, it is inferred to be equal to 0. When vps_independent_layer_flag[i] is equal to 0, there shall be at least one value of j in the range of 0 to i−1, inclusive, such that the value of vps_direct_ref_layer_flag[i][j] is equal to 1. The variables NumDirectRefLayers[i], DirectRefLayerIdx[i][d], NumRefLayers[i], RefLayerIdx[i][r], and LayerUsedAsRefLayerFlag[j] are derived as follows:

for( i = 0; i <= vps_max_layers_minus1; i++ ) {  for( j = 0; j <= vps_max_layers_minus1; j++ ) {   dependencyFlag[ i ][ j ] = vps_direct_ref_layer_flag[ i ][ j ]   for( k = 0, k < i; k++ )    if( vps_direct_ref_layer_flag[ i ][ k ] && dependencyFlag[ k ][    j ] )     dependencyFlag[ i ][ j ] = 1  }  LayerUsedAsRefLayerFlag[ i ] = 0 } for( i = 0; i <= vps_max_layers_minus1; i++ ) {  for( j = 0, d = 0, r = 0; j <= vps_max_layers_minus1; j++ ) { (37)   if( vps_direct_ref_layer_flag[ i ][ j ] ) {    DirectRefLayerIdx[ i ][ d++ ] = j    LayerUsedAsRefLayerFlag[ j ] = 1   }   if( dependencyFlag[ i ][ j ] )    RefLayerIdx[ i ][ r++ ] = j  }  NumDirectRefLayers[ i ] = d  NumRefLayers[ i ] = r } The variable GeneralLayerIdx[i], specifying the layer index of the layer with nuh_layer_id equal to vps_layer_id[i], is derived as follows:

for(i=0;i<=vps_max_layers_minus1;i++)GeneralLayerIdx[vps_layer_id[i]]=i  (38)

For any two different values of i and j, both in the range of 0 to vps_max_layers_minus1, inclusive, when dependencyFlag[i][j] equal to 1, it is a requirement of bitstream conformance that the values of chroma_format_idc and bit_depth_minus8 that apply to the i-th layer shall be equal to the values of chroma_format_idc and bit_depth_minus8, respectively, that apply to the j-th layer. max_tid_ref_present_flag[i] equal to 1 specifies that the syntax element max_tid_il_ref_pics_plus1[i] is present. max_tid_ref_present_flag[i] equal to 0 specifies that the syntax element max_tid_il_ref_pics_plus1[i] is not present. max_tid_il_ref_pics_plus1[i] equal to 0 specifies that inter-layer prediction is not used by non-IRAP pictures of the i-th layer. max_tid_il_ref_pics_plus1[i] greater than 0 specifies that, for decoding pictures of the i-th layer, no picture with TemporalId greater than max_tid_il_ref_pics_plus1[i]−1 is used as ILRP. When not present, the value of max_tid_il_ref_pics_plus1[i] is inferred to be equal to 7. each_layer_is_an_ols_flag equal to 1 specifies that each OLS contains only one layer and each layer itself in a CVS referring to the VPS is an OLS with the single included layer being the only output layer. each_layer_is_an_ols_flag equal to 0 that an OLS may contain more than one layer. If vps_max_layers_minus1 is equal to 0, the value of each_layer_is_an_ols_flag is inferred to be equal to 1. Otherwise, when vps_all_independent_layers_flag is equal to 0, the value of each_layer_is_an_ols_flag is inferred to be equal to 0. ols_mode_idc equal to 0 specifies that the total number of OLSs specified by the VPS is equal to vps_max_layers_minus1+1, the i-th OLS includes the layers with layer indices from 0 to i, inclusive, and for each OLS only the highest layer in the OLS is output. ols_mode_idc equal to 1 specifies that the total number of OLSs specified by the VPS is equal to vps_max_layers_minus1+1, the i-th OLS includes the layers with layer indices from 0 to i, inclusive, and for each OLS all layers in the OLS are output. ols_mode_idc equal to 2 specifies that the total number of OLSs specified by the VPS is explicitly signalled and for each OLS the output layers are explicitly signalled and other layers are the layers that are direct or indirect reference layers of the output layers of the OLS. The value of ols_mode_idc shall be in the range of 0 to 2, inclusive. The value 3 of ols_mode_idc is reserved for future use by ITU-T|ISO/IEC. When vps_all_independent_layers_flag is equal to 1 and each_layer_is_an_ols_flag is equal to 0, the value of ols_mode_idc is inferred to be equal to 2. num_output_layer_sets_minus1 plus 1 specifies the total number of OLSs specified by the VPS when ols_mode_idc is equal to 2. The variable TotalNumOlss, specifying the total number of OLSs specified by the VPS, is derived as follows:

if( vps_max_layers_minus1 = = 0 )  TotalNumOlss = 1 else if( each_layer_is_an_ols_flag | | ols_mode_idc = = 0 | | ols_mode_idc = = 1 )  TotalNumOlss = vps_max_layers_minus1 + 1 (39) else if( ols_mode_idc = = 2 )  TotalNumOlss = num_output_layer_sets_minus1 + 1 ols_output_layer_flag[i][j] equal to 1 specifies that the layer with nuh_layer_id equal to vps_layer_id[j] is an output layer of the i-th OLS when ols_mode_idc is equal to 2. ols_output_layer_flag[1][j] equal to 0 specifies that the layer with nuh_layer_id equal to vps_layer_id[j] is not an output layer of the i-th OLS when ols_mode_idc is equal to 2.

The variable NumOutputLayersInOls[i], specifying the number of output layers in the i-th OLS, the variable NumSubLayersInLayerInOLS[i][j], specifying the number of sublayers in the j-th layer in the i-th OLS, the variable OutputLayerIdInOls[i][j], specifying the nuh_layer_id value of the j-th output layer in the i-th OLS, and the variable LayerUsedAsOutputLayerFlag[k], specifying whether the k-th layer is used as an output layer in at least one OLS, are derived as follows:

NumOutputLayersInOls[ 0 ] = 1 OutputLayerIdInOls[ 0 ][ 0 ] = vps_layer_id[ 0 ] NumSubLayersInLayerInOLS[ 0 ][ 0 ] = vps_max_sub_layers_minus1 + 1 LayerUsedAsOutputLayerFlag[ 0 ] = 1 for( i = 1, i <= vps_max_layers_minus1; i++ ) {  if( each_layer_is_an_ols_flag | | ols_mode_idc < 2 )  LayerUsedAsOutputLayerFlag[ i ] = 1  else /*( !each_layer_is_an_ols_flag && ols_mode_idc = = 2 ) */  LayerUsedAsOutputLayerFlag[ i ] = 0 } for( i = 1; i < TotalNumOlss; i++ )  if( each_layer_is_an_ols_flag | | ols_mode_idc = = 0 ) {  NumOutputLayersInOls[ i ] = 1  OutputLayerIdInOls[ i ][ 0 ] = vps_layer_id[ i ]  for( j = 0; j < i && ( ols_mode_idc = = 0 ); j++ )   NumSubLayersInLayerInOLS[ i ][ j ] =   max_tid_il_ref_pics_plus1[ i ]  NumSubLayersInLayerInOLS[ i ][ i ] =  vps_max_sub_layers_minus1 + 1  } else if( ols_mode_idc = 1 ) {  NumOutputLayersInOls[ i ] = i + 1  for( j = 0, j < NumOutputLayersInOls[ i ], j++ ) {   OutputLayerIdInOls[ i ][ j ] = vps_layer_id[ j ]   NumSubLayersInLayerInOLS[ i ][ j ] =   vps_max_sub_layers_minus1 + 1  }  } else if( ols_mode_idc = = 2 ) {  for( j = 0; j <= vps_max_layers_minus1; j++ ) {   layerIncludedInOlsFlag[ i ][ j ] = 0   NumSubLayersInLayerInOLS[ i ][ j ] = 0  }  for( k = 0, j = 0; k <= vps_max_layers_minus1; k++ ) (40)   if( ols_output_layer_flag[ i ][ k ] ) {   layerIncludedInOlsFlag[ i ][ k ] = 1   LayerUsedAsOutputLayerFlag[ k ] = 1   OutputLayerIdx[ i ][ j ] = k   OutputLayerIdInOls[ i ][ j++ ] = vps_layer_id[ k ]   NumSubLayersInLayerInOLS[ i ][ j ] = vps_max_sub_layers_minus1 + 1   }  NumOutputLayersInOls[ i ] = j  for( j = 0; j < NumOutputLayersInOls[ i ]; j++ ) {   idx = OutputLayerIdx[ i ][ j ]   for( k = 0; k < NumRefLayers[ idx ]; k++ ) {   layerIncludedInOlsFlag[ 1 ][ RefLayerIdx[ idx ][ k ] ] = 1   if( NumSubLayersInLayerInOLS[ i ][ RefLayerIdx[ idx ][ k ] ] <  max_tid_il_ref_pics_plus1[ OutputLayerIdInOls[ i ][ j ] ] )    NumSubLayersInLayerInOLS[ i ][ RefLayerIdx[ idx ][ k ] ] =    max_tid_il_ref_pics_plus1[ OutputLayerIdInOls[ i ][ j ] ]   }  }  } For each value of i in the range of 0 to vps_max_layers_minus1, inclusive, the values of LayerUsedAsRefLayerFlag[i] and LayerUsedAsOutputLayerFlag[i] shall not be both equal to 0. In other words, there shall be no layer that is neither an output layer of at least one OLS nor a direct reference layer of any other layer. For each OLS, there shall be at least one layer that is an output layer. In other words, for any value of i in the range of 0 to TotalNumOlss−1, inclusive, the value of NumOutputLayersInOls[i] shall be greater than or equal to 1. The variable NumLayersInOls[i], specifying the number of layers in the i-th OLS, and the variable LayerIdInOls[i][j], specifying the nuh_layer_id value of the j-th layer in the i-th OLS, are derived as follows:

NumLayersInOls[ 0 ] = 1 LayerIdInOls[ 0 ][ 0 ] = vps_layer_id[ 0 ] for( i = 1; i < TotalNumOlss; i++ ) {  if( each_layer_is_an_ols_flag ) {   NumLayersInOls[ i ] = 1   LayerIdInOls[ i ][ 0 ]= vps_layer_id[ i ] (41)  } else if( ols_mode_idc = = 0 | | ols_mode_idc = = 1 ) {   NumLayersInOls[ i ] = i + 1   for( j = 0; j < NumLayersInOls[ i ]; j++ )    LayerIdInOls[ i ][ j ] = vps_layer_id[ j ]  } else if( ols_mode_idc = = 2 ) {   for( k = 0, j = 0; k <= vps_max_layers_minus1; k++ )    if( layerIncludedInOlsFlag[ i ][ k ] )    LayerIdInOls[ i ][ j++ ] = vps_layer_id[ k ]   NumLayersInOls[ i ] = j  } }

-   -   NOTE 1—The 0-th OLS contains only the lowest layer (i.e., the         layer with nuh_layer_id equal to vps_layer_id[0]) and for the         0-th OLS the only included layer is output.         The variable OlsLayerIdx[i][j], specifying the OLS layer index         of the layer with nuh_layer_id equal to LayerIdInOls[i][j], is         derived as follows:

for( i = 0; i < TotalNumOlss; i++ )  for j = 0; j < NumLayersInOls[ i ]; j++ ) (42)   OlsLayerIdx[ i ][ LayerIdInOls[ i ][ j ] ] = j The lowest layer in each OLS shall be an independent layer. In other words, for each i in the range of 0 to TotalNumOlss−1, inclusive, the value of vps_independent_layer_flag[GeneralLayerIdx[LayerIdInOls[i][0]]] shall be equal to 1. Each layer shall be included in at least one OLS specified by the VPS. In other words, for each layer with a particular value of nuh_layer_id nuhLayerId equal to one of vps_layer_id[k] for k in the range of 0 to vps_max_layers_minus1, inclusive, there shall be at least one pair of values of i and j, where i is in the range of 0 to TotalNumOlss−1, inclusive, and j is in the range of NumLayersInOls[i]−1, inclusive, such that the value of LayerIdInOls[i][j] is equal to nuhLayerId. vps_num_ptls_minus1 plus 1 specifies the number of profile_tier_level( ) syntax structures in the VPS. The value of vps_num_ptls_minus1 shall be less than TotalNumOlss. pt_present_flag[i] equal to 1 specifies that profile, tier, and general constraints information are present in the i-th profile_tier_level( ) syntax structure in the VPS. pt_present_flag[i] equal to 0 specifies that profile, tier, and general constraints information are not present in the i-th profile_tier_level( ) syntax structure in the VPS. The value of pt_present_flag[0] is inferred to be equal to 1. When pt_present_flag[i] is equal to 0, the profile, tier, and general constraints information for the i-th profile_tier_level( ) syntax structure in the VPS are inferred to be the same as that for the (i−1)-th profile_tier_level( ) syntax structure in the VPS. ptl_max_temporal_id[i] specifies the TemporalId of the highest sublayer representation for which the level information is present in the i-th profile_tier_level( ) syntax structure in the VPS. The value of ptl_max_temporal_id[i] shall be in the range of 0 to vps_max_sublayers_minus1 inclusive. When vps_max_sublayers_minus1 is equal to 0, the value of ptl_max_temporal_id[i] is inferred to be equal to 0. When vps_max_sublayers_minus1 is greater than 0 and vps_all_layers_same_num_sublayers_flag is equal to 1, the value of ptl_max_temporal_id[i] is inferred to be equal to vps_max_sublayers_minus1. vps_ptl_alignment_zero_bit shall be equal to 0. ols_ptl_idx[i] specifies the index, to the list of profile_tier_level( ) syntax structures in the VPS, of the profile_tier_level( ) syntax structure that applies to the 1-th OLS. When present, the value of ols_ptl_idx[i] shall be in the range of 0 to vps_num_ptls_minus1, inclusive. When vps_num_ptls_minus1 is equal to 0, the value of ols_ptl_idx[i] is inferred to be equal to 0. When NumLayersInOls[i] is equal to 1, the profile_tier_level( ) syntax structure that applies to the i-th OLS is also present in the SPS referred to by the layer in the i-th OLS. It is a requirement of bitstream conformance that, when NumLayersInOls[i] is equal to 1, the profile_tier_level( ) syntax strictures signalled in the VPS and in the SPS for the i-th OLS shall be identical. vps_num_dpb_params specifies the number of dpb_parameters( ) syntax structures in the VPS. The value of vps_num_dpb_params shall be in the range of 0 to 16, inclusive. When not present, the value of vps_num_dpb_params is inferred to be equal to 0. vps_sublayer_dpb_params_present_flag is used to control the presence of max_dec_pic_buffering_minus1[ ], max_num_reorder_pics[ ], and max_latency_increase_plus1[ ] syntax elements in the dpb_parameters( ) syntax structures in the VPS. When not present vps_sub_dpb_params_info_present_flag is inferred to be equal to 0. dpb_max_temporal_id[i] specifies the TemporalId of the highest sublayer representation for which the DPB parameters may be present in the i-th dpb_parameters( ) syntax structure in the VPS. The value of dpb_max_temporal_id[i] shall be in the range of 0 to vps_max_sublayers_minus1, inclusive. When vps_max_sublayers_minus1 is equal to 0, the value of dpb_max_temporal_id[i] is inferred to be equal to 0. When vps_max_sublayers_minus1 is greater than 0 and vps_all_layers_same_num_sublayers_flag is equal to 1, the value of dpb_max_temporal_id[i] is inferred to be equal to vps_max_sublayers_minus1. ols_dpb_pic_width[i] specifies the width, in units of luma samples, of each picture storage buffer for the i-th OLS. ols_dpb_pic_height[i] specifies the height in units of luma samples, of each picture storage buffer for the i-th OLS. ols_dpb_params_idx[i] specifies the index, to the list of dpb_parameters( ) syntax structures in the VPS, of the dpb_parameters( ) syntax structure that applies to the i-th OLS when NumLayersInOls[i] is greater than 1. When present, the value of ols_dpb_params_idx[i] shall be in the range of 0 to vps_num_dpb_params−1, inclusive. When ols_dpb_params_idx[i] is not present, the value of ols_dpb_params_idx[i] is inferred to be equal to 0. When NumLayersInOls[i] is equal to 1, the dpb_parameters( ) syntax structure that applies to the i-th OLS is present in the SPS referred to by the layer in the i-th OLS. vps_general_hrd_params_present_flag equal to 1 specifies that the syntax structure general_hrd_parameters( ) and other HRD parameters are present in the VPS RBSP syntax structure. vps_general_hrd_params_present_flag equal to 0 specifies that the syntax structure general_hrd_parameters( ) and other HRD parameters are not present in the VPS RBSP syntax structure. When not present, the value of vps_general_hrd_params_present_flag is inferred to be equal to 0. When NumLayersInOls[i] is equal to 1, the general_hrd_parameters( ) syntax structure that applies to the i-th OLS is present in the SPS referred to by the layer in the i-th OLS. vps_sublayer_cpb_params_present_flag equal to 1 specifies that the i-th ols_hrd_parameters( ) syntax structure in the VPS contains HRD parameters for the sublayer representations with TemporalId in the range of 0 to hrd_max_tid[i], inclusive. vps_sublayer_cpb_params_present_flag equal to 0 specifies that the i-th ols_hrd_parameters( ) syntax structure in the VPS contains HRD parameters for the sublayer representation with TemporalId equal to hrd_max_tid[i] only. When vps_max_sublayers_minus1 is equal to 0, the value of vps_sublayer_cpb_params_present_flag is inferred to be equal to 0. When vps_sublayer_cpb_params_present_flag is equal to 0, the HRD parameters for the sublayer representations with TemporalId in the range of 0 to hrd_max_tid[i]−1, inclusive, are inferred to be the same as that for the sublayer representation with TemporalId equal to hrd_max_tid[i]. These include the HRD parameters starting from the fixed_pic_rate_general_flag[i] syntax element till the sublayer_hrd_parameters(i) syntax structure immediately under the condition “if(general_vcl_hrd_params_present_flag)” in the ols_hrd_parameters syntax structure. num_ols_hrd_params_minus1 plus 1 specifies the number of ols_hrd_parameters( ) syntax structures present in the general_hrd_parameters( ) syntax structure when vps_general_hrd_params_present_flag is equal to 1. The value of num_ols_hrd_params_minus1 shall be in the range of 0 to TotalNumOlss−1, inclusive. hrd_max_tid[i] specifies the TemporalId of the highest sublayer representation for which the HRD parameters are contained in the i-th ols_hrd_parameters( ) syntax structure. The value of hrd_max_tid[i] shall be in the range of 0 to vps_max_sublayers_minus1, inclusive. When vps_max_sublayers_minus1 is equal to 0, the value of hrd_max_tid[i] is inferred to be equal to 0. When vps_max_sublayers_minus1 is greater than 0 and vps_all_layers_same_num_sublayers_flag is equal to 1, the value of hrd_max_tid[i] is inferred to be equal to vps_max_sublayers_minus1. ols_hrd_idx[i] specifies the index, to the list of ols_hrd_parameters( ) syntax structures in the VPS, of the ols_hrd_parameters( ) syntax structure that applies to the i-th OLS when NumLayersInOls[i] is greater than 1. The value of ols_hrd_idx[[i] shall be in the range of 0 to num_ols_hrd_params_minus1, inclusive. When NumLayersInOls[i] is equal to 1, the ols_hrd_parameters( ) syntax structure that applies to the i-th OLS is present in the SPS referred to by the layer in the i-th OLS. If the value of num_ols_hrd_param_minus1+1 is equal to TotalNumOlss, the value of ols_hrd_idx[i] is inferred to be equal to i. Otherwise, when NumLayersInOls[i] is greater than 1 and num_ols_hrd_params_minus1 is equal to 0, the value of ols_hrd_idx[[i] is inferred to be equal to 0. vps_extension_flag equal to 0 specifies that no vps_extension_data_flag syntax elements are present in the VPS RBSP syntax structure. vps_extension_flag equal to 1 specifies that there are vps_extension_data_flag syntax elements present in the VPS RBSP syntax structure. vps_extension_data_flag may have any value. Its presence and value do not affect decoder conformance to profiles specified in this version of this Specification. Decoders conforming to this version of this Specification shall ignore all vps_exension_data_flag syntax elements.

3.5. SPS Syntax and Semantics

In the latest VVC draft text, the SPS syntax and semantics are as follows:

Descriptor seq_parameter_set_rbsp( ) {  sps_seq_parameter_set_id u(4)  sps_video_parameter_set_id u(4)  sps_max_sublayers_minus1 u(3)  sps_reserved_zero_4bits u(4)  sps_ptl_dpb_hrd_params_present_flag u(1)  if( sps_ptl_dpb_hrd_params_present_flag )   profile_tier_level( 1, sps max_sublayers_minus1 )  gdr_enabled_flag u(1)  chroma_format_idc u(2)  if( chroma_format_idc = = 3 )   separate_colour_plane_flag u(1)  res_change_in_clvs_allowed_flag u(1)  pic_width_max_in_luma_samples ue(v)  pic_height_max_in_luma_samples ue(v)  sps_conformance_window_flag u(1)  if( sps_conformance_window_flag ) {   sps_conf_win_left_offset ue(v)   sps_conf_win_right_offset ue(v)   sps_conf_win_top_offset ue(v)   sps_conf_win_bottom_offset ue(v)  }  sps_log2_ctu_size_minus5 u(2)  subpic_info_present_flag u(1)  if( subpic_info_present_flag ) {   sps_num_subpics_minus1 ue(v)   sps_independent_subpics_flag u(1)   for( i = 0; sps_num_subpics_minus1 > 0 && i <= sps_num_subpics_minus1; i++ ) {    if( i > 0 && pic_width_max_in_luma_samples > CtbSizeY )     subpic_ctu_top_left_x[ i ] u(v)    if( i > 0 && pic_height_max_in_luma_samples > CtbSizeY ) {     subpic_ctu_top_left_y[ i ] u(v)    if( i < sps_num_subpics_minus1 &&      pic_width_max_in_luma_samples > CtbSizeY )     subpic_width_minus1[ i ] u(v)    if( i < sps_num_subpics_minus1 &&      pic_height_max_in_luma_samples > CtbSizeY )     subpic_height_minus1[ i ] u(v)    if( !sps_independent_subpics_flag) {     subpic_treated_as_pic_flag[ i ] u(1)     loop_filter_across_subpic_enabled_flag[ i ] u(1)    }   }   sps_subpic_id_len_minus1 ue(v)   subpic_id_mapping_explicitly_signalled_flag u(1)   if( subpic_id_mapping_explicitly_signalled_flag ) {    subpic_id_mapping_in_sps_flag u(1)    if( subpic_id_mapping_in_sps_flag )     for( i = 0; i <= sps_num_subpics_minus1; i++ )      sps_subpic_id[ i ] u(v)   }  }  bit_depth_minus8 ue(v)  sps_entropy_coding_sync_enabled_flag u(1)  if( sps_entropy_coding_sync_enabled_flag )   sps_wpp_entry_point_offsets_present_flag u(1)  sps_weighted_pred_flag u(1)  sps_weighted_bipred_flag u(1)  log2_max_pic_order_cnt_lsb_minus4 u(4)  sps_poc_msb_flag u(1)  if( sps_poc_msb_flag )   poc_msb_len_minus1 ue(v)  num_extra_ph_bits_bytes u(2)   extra_ph_bits_struct( num_extra_ph_bits_bytes )  num_extra_sh_bits_bytes u(2)   extra_sh_bits_struct( num_extra_sh_bits_bytes )  if( sps_max_sublayers_minus1 > 0 )   sps_sublayer_dpb_params_flag u(1)  if( sps_ptl_dpb_hrd_params_present_flag )   dpb_parameters( sps_max_sublayers_minus1, sps_sublayer_dpb_params_flag )  long_term_ref_pics_flag u(1)  inter_layer_ref_pics_present_flag u(1)  sps_idr_rpl_present_flag u(1)  rpl1_same_as_rpl0_flag u(1)  for( i = 0; i < !rpl1_same_as_rpl0_flag ? 2 : 1; i++ ) {   num_ref_pic_lists_in_sps[ i ] ue(v)     delta_qp_in_val_minus1[ i ][ j ] ue(v)     delta_qp_diff_val[ i ][ j ] ue(v)    }   }  }  sps_sao_enabled_flag u(1)  sps_alf_enabled_flag u(1)  if( sps_alf_enabled_flag && ChromaArrayType != 0 )   sps_ccalf_enabled_flag u(1)  sps_transform_skip_enabled_flag u(1)  if( sps_transform_skip_enabled_flag ) {   log2_transform_skip_max_size_minus2 ue(v)   sps_bdpcm_enabled_flag u(1)  }  sps_ref_wraparound_enabled_flag u(1)  sps_temporal_mvp_enabled_flag u(1)  if( sps_temporal_mvp_enabled_flag )   sps_sbtmvp_enabled_flag u(1)  sps_amvr_enabled_flag u(1)  sps_bdof_enabled_flag u(1)  if( sps_bdof_enabled_flag )   sps_bdof_pic_present_flag u(1)  sps_smvd_enabled_flag u(1)  sps_dmvr_enabled_flag u(1)  if( sps_dmvr_enabled_flag)   sps_dmvr_pic_present_flag u(1)  sps_mmvd_enabled_flag u(1)  sps_isp_enabled_flag u(1)  sps_mrl_enabled_flag u(1)  sps_mip_enabled_flag u(1)  if( ChromaArrayType != 0 )   sps_cclm_enabled_flag u(1)  if( chroma_format_idc = = 1 ) {   sps_chroma_horizontal_collocated_flag u(1)   sps_chroma_vertical_collocated_flag u(1)  }  sps_mts_enabled_flag u(1)  if( sps_mts_enabled_flag ) {   sps_explicit_mts_intra_enabled_flag u(1)   sps_explicit_mts_inter_enabled_flag u(1)  }  six_minus_max_num_merge_cand ue(v)  sps_sbt_enabled_flag u(1)  sps_affine_enabled_flag u(1)  if( sps_affine_enabled_flag ) {   five_minus_max_num_subblock_merge_cand ue(v)   sps_affine_type_flag u(1)   if( sps_amvr_enabled_flag )    sps_affine_amvr_enabled_flag u(1)   sps_affine_prof_enabled_flag u(1)   if( sps_affine_prof_enabled_flag )    sps_prof_pic_present_flag u(1)  }  sps_palette_enabled_flag u(1)  if( ChromaArrayType = = 3 && !sps_max_luma_transform_size_64_flag )   sps_act_enabled_flag u(1)  if( sps_transform_skip_enabled_flag | | sps_palette_enabled_flag )   min_qp_prime_ts_minus4 ue(v)  sps_bcw_enabled_flag u(1)  sps_ibc_enabled_flag u(1)  if( sps_ibc_enabled_flag )   six_minus_max_num_ibc_merge_cand ue(v)  sps_ciip_enabled_flag u(1)  if( sps_mmvd_enabled_flag )   sps_fpel_mmvd_enabled_flag u(1)  if( MaxNumMergeCand >= 2 ) {   sps_gpm_enabled_flag u(1)   if( sps_gpm_enabled_flag && MaxNumMergeCand >= 3 )    max_num_merge_cand_minus_max_num_gpm_cand ue(v)  }  sps_lmcs_enabled_flag u(1)  sps_lfnst_enabled_flag u(1)  sps_ladf_enabled_flag u(1)  if( sps_ladf_enabled_flag ) {   sps_num_ladf_intervals_minus2 u(2)   sps_ladf_lowest_interval_qp_offset se(v)   for( i = 0; i < sps_num_ladf_intervals_minus2 + 1; i++ ) {    sps_ladf_qp_offset[ i ] se(v)    sps_ladf_delta_threshold_minus1[ i ] ue(v)   }  }  log2_parallel_merge_level_minus2 ue(v)  sps_scaling_list_enabled_flag u(1)  sps_dep_quant_enabled_flag u(1)  if( !sps_dep_quant_enabled_flag )   sps_sign_data_hiding_enabled_flag u(1)  sps_virtual_boundaries_enabled_flag u(1)  if( sps_virtual_boundaries_enabled_flag ) {   sps_virtual_boundaries_present_flag u(1)   if( sps_virtual_boundaries_present_flag ) {    sps_num_ver_virtual_boundaries u(2)    for( i = 0; i < sps_num_ver_virtual_boundaries; i++ )     sps_virtual_boundaries_pos_x[ i ] u(13)    sps_num_hor_virtual_boundaries u(2)    for( i = 0; i < sps_num_hor_virtual_boundaries; i++ )     sps_virtual_boundaries_pos_y[ i ] u(13)   }  }  if( sps_ptl_dpb_hrd_params_present_flag ) {   sps_general_hrd_params_present_flag u(1)   if( sps_general_hrd_params_present_flag ) {    general_hrd_parameters( )    if( sps_max_sublayers_minus1 > 0 )     sps_sublayer_cpb_params_present_flag u(1)    firstSubLayer = sps_sublayer_cpb_params_present_flag ? 0 :      sps_max_sublayers_minus1    ols_hrd_parameters( firstSubLayer, sps_max_sublayers_minus1 )   }  }  field_seq_flag u(1)  vui_parameters_present_flag u(1)  if( vui_parameters_present_flag )   vui_parameters( ) /* Specified in ITU-T H.SEI | ISO/IEC 23002-7 */  sps_extension_flag u(1)  if( sps_extension_flag )   while( more_rbsp_data( ) )    sps_extension_data_flag u(1)  rbsp_trailing_bits( ) } An SPS RBSP shall be available to the decoding process prior to it being referenced, included in at least one AU with TemporalId equal to 0 or provided through external means. All SPS NAL units with a particular value of sps_seq_parameter_set_id in a CVS shall have the same content. sps_seq_parameter_set_id provides an identifier for the SPS for reference by other syntax elements. SPS NAL units, regardless of the nuh_layer_id values, share the same value space of sps_seq_parameter_set_id. Let spsLayerId be the value of the nuh_layer_id of a particular SPS NAL unit, and vclLayerId be the value of the nuh_layer_id of a particular VCL NAL unit. The particular VCL NAL unit shall not refer to the particular SPS NAL unit unless spsLayerId is less than or equal to vclLayerId and the layer with nuh_layer_id equal to spsLayerId is included in at least one OLS that includes the layer with nuh_layer_id equal to vclLayerId. sps_video_parameter_set_id, when greater than 0, specifies the value of vps_video_parameter_set_id for the VPS referred to by the SPS. When sps_video_parameter_set_id is equal to 0, the following applies:

-   -   The SPS does not refer to a VPS.     -   No VPS is referred to when decoding each CLVS referring to the         SPS.     -   The value of vps_max_layers_minus1 is inferred to be equal to 0.     -   The CVS shall contain only one layer (i.e., all VCL NAL unit in         the CVS shall have the same value of nuh_layer_id).     -   The value of GeneralLayerIdx[nuh_layer_id] is inferred to be         equal to 0.     -   The value of         vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is         inferred to be equal to 1.         When vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]]         is equal to 1, the SPS referred to by a CLVS with a particular         nuh_layer_id value nuhLayerId shall have nuh_layer_id equal to         nuhLayerId.         The value of sps_video_parameter_set_id shall be the same in all         SPSs that are referred to by CLVSs in a CVS.         sps_max_sublayers_minus1 plus 1 specifies the maximum number of         temporal sublayers that may be present in each CLVS referring to         the SPS. The value of sps_max_sublayers_minus1 shall be in the         range of 0 to vps_max_sublayers_minus1, inclusive.         sps_reserved_zero_4bits shall be equal to 0 in bitstreams         conforming to this version of this Specification. Other values         for sps_reserved_zero_4bits are reserved for future use by         ITU-T|ISO/IEC.         sps_ptl_dpb_hrd_params_present_flag equal to 1 specifies that a         profile_tier_level( ) syntax structure and a dpb_parameters( )         syntax structure are present in the SPS, and a         general_hrd_parameters( ) syntax structure and an         ols_hrd_parameters( ) syntax structure may also be present in         the SPS. sps_ptl_dpb_hrd_params_present_flag equal to 0         specifies that none of these four syntax structures is present         in the SPS. The value of sps_ptl_dpb_hrd_params_present_flag         shall be equal to         vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]].         gdr_enabled_flag equal to 1 specifies that GDR pictures may be         present in CLVSs referring to the SPS. gdr_enabled_flag equal to         0 specifies that GDR pictures are not present in CLVSs referring         to the SPS.         chroma_format_idc specifies the chroma sampling relative to the         luma sampling as specified in clause 6.2.         separate_colour_plane_flag equal to 1 specifies that the three         colour components of the 4:4:4 chroma format are coded         separately, separate_colour_plane_flag equal to 0 specifies that         the colour components are not coded separately. When         separate_colour_plane_flag is not present, it is inferred to be         equal to 0. When separate_colour_plane_flag is equal to 1, the         coded picture consists of three separate components, each of         which consists of coded samples of one colour plane (Y, Cb. or         Cr) and uses the monochrome coding syntax. In this case, each         colour plane is associated with a specific colour_plane_id         value.     -   NOTE 1—There is no dependency in decoding processes between the         colour planes having different colour_plane_id values. For         example, the decoding process of a monochrome picture with one         value of colour_plane_id does not use any data from monochrome         pictures having different values of colour_plane_id for inter         prediction.         Depending on the value of separate_colour_plane_flag, the value         of the variable ChromaArrayType is assigned as follows:     -   If separate_colour_plane_flag is equal to 0, ChromaArrayType is         set equal to chroma_format_idc.     -   Otherwise (separate_colour_plane_flag is equal to 1),         ChromaArrayType is set equal to 0.         res_change_in_clvs_allowed_flag equal to 1 specifies that the         picture spatial resolution may change within a CLVS referring to         the SPS. res_change_in_clvs_allowed_flag equal to 0 specifies         that the picture spatial resolution does not change within any         CLVS referring to the SPS.         pic_width_max_in_luma_samples specifies the maximum width, in         units of luma samples, of each decoded picture referring to the         SPS. pic_width_max_in_luma_samples shall not be equal to 0 and         shall be an integer multiple of Max(8, MinCbSizeY).         It is a requirement of bitstream conformance that, for any OLS         with OLS index i that contains one or more layers that refers to         the SPS, the value of pic_width_max_in_luma_samples shall be         less than or equal to the value of ols_dpb_pic_width[i].         pic_height_max_in_luma_samples specifies the maximum height, in         units of luma samples, of each decoded picture referring to the         SPS. pic_height_max_in_luma_samples shall not be equal to 0 and         shall be an integer multiple of Max(8, MinCbSizeY).         It is a requirement of bitstream conformance that, for any OLS         with OLS index i that contains one or more layers that refers to         the SPS, the value of pic_height_max_in_luma_samples shall be         less than or equal to the value of ols_dpb_pic_height[i].         sps_conformance_window_flag equal to 1 indicates that the         conformance cropping window offset parameters follow next in the         SPS. sps_conformance_window_flag equal to 0 indicates that the         conformance cropping window offset parameters are not present in         the SPS.         sps_conf_win_left_offset, sps_conf_win_right_offset,         sps_conf_win_top_offset, and sps_conf_win_bottom_offset specify         the cropping window that is applied to pictures with         pic_width_in_luma_samples equal to pic_width_max_in_luma_samples         and pic_height_in_luma_samples equal to         pic_height_max_in_luma_samples. When sps_conformance_window_flag         is equal to 0, the values of sps_conf_win_left_offset,         sps_conf_win_right_offset, sps_conf_win_top_offset, and         sps_conf_win_bottom_offset are inferred to be equal to 0.         The conformance cropping window contains the luma samples with         horizontal picture coordinates from         SubWidthC*sps_conf_win_left_offset to         pic_width_max_in_luma_samples−(SubWidthC*sps_conf_win_right_offset+1)         and vertical picture coordinates from         SubHeightC*sps_conf_win_top_offset to         pic_height_max_in_luma_samples−(SubHeightC*sps_conf_win_bottom_offset+1),         inclusive. The value of         SubWidthC*(sps_conf_win_left_offset+sps_conf_win_right_offset)         shall be less than pic_width_max_in_luma_samples, and the value         of         SubHeightC*(sps_conf_win_top_offset+sps_conf_win_bottom_offset)         shall be less than pic_height_max_in_luma_samples.         When ChromaArrayType is not equal to 0, the corresponding         specified samples of the two chroma arrays are the samples         having picture coordinates (x/SubWidthC, y/SubHeightC), where         (x, y) are the picture coordinates of the specified luma         samples.     -   NOTE 2—The conformance cropping window offset parameters are         only applied at the output. All internal decoding processes are         applied to the =cropped picture sire.         sps_log2_ctu_size_minus5 plus 5 specifies the luma coding tree         block size of each CTU. The value of sps_log2_ctu_size_minus5         shall be in the range of 0 to 2, inclusive. The value 3 for         sps_log2_ctu_size_minus5 is reserved for future use by         ITU-T|ISO/IEC.         The variables CtbLog2SizeY and CtbSizeY are derived as follows:

CtbLog2SizeY=sps_log2_ctu_size_minus5+5  (43)

CtbSizeY=1<<CtbLog2SizeY  (44)

subpic_info_present_flag equal to 1 specifies that subpicture information is present for the CLVS and there may be one or more than one subpicture in each picture of the CLVS. subpic_info_present_flag equal to 0 specifies that subpicture information is not present for the CLVS and there is only one subpicture in each picture of the CLVS. When res_change_in_clvs_allowed_flag is equal to 1, the value of subpic_info_present_flag shall be equal to 0.

-   -   NOTE 3—When a bitstream is the result of a sub-bitstream         extraction process and contains only a subset of the subpictures         of the input bitstream to the sub-bitstream extraction process,         it might be required to set the value of         subpic_info_present_flag equal to 1 in the RBSP of the SPSs.         sps_num_subpics_minus1 plus 1 specifies the number of         subpictures in each picture in the CLVS. The value of         sps_num_subpics_minus1 shall be in the range of 0 to         Ceil(pic_width_max_in_luma_samples_CtbSizeY)*Ceil(pic_height_max_in_luma_samples_CtbSizeY)−1,         inclusive. When not present, the value of sps_num_subpics_minus1         is inferred to be equal to 0.         sps_independent_subpics_flag equal to 1 specifies that no intra         prediction, no inter prediction and no in-loop filtering         operations may be performed across any subpicture boundary in         the CLVS. sps_independent_subpics_flag equal to 0 specifies that         inter prediction or in-loop filtering operations across the         subpicture boundaries in the CLVS may be allowed. When not         present, the value of sps_independent_subpics_flag is inferred         to be equal to 0.         subpic_ctu_top_left_x[i] specifies horizontal position of top         left CTU of i-th subpicture in unit of CtbSizeY. The length of         the syntax element is         Ceil(Log2((pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY))         bits. When not present, the value of subpic_ctu_top_left_x[i] is         inferred to be equal to 0.         subpic_ctu_top_left_y[i] specifies vertical position of top left         CTU of i-th subpicture in unit of CtbSizeY. The length of the         syntax element is         Ceil(Log2((pic_height_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY))         bits. When not present, the value of subpic_ctu_top_left_y[i] is         inferred to be equal to 0.         subpic_width_minus1[i] plus 1 specifies the width of the i-th         subpicture in units of CtbSizeY. The length of the syntax         element is         Ceil(Log2((pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY))         bits. When not present, the value of subpic_width_minus1[i] is         inferred to be equal to         ((pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY)−subpic_ctu_top_left_x[i]−1.         subpic_height_minus1[i] plus 1 specifies the height of the i-th         subpicture in units of CtbSizeY. The length of the syntax         element is         Ceil(Log2((pic_height_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY))         bits. When not present, the value of subpic_height_minus1[i] is         inferred to be equal to         ((pic_height_max_in_luma_samples+CtbSizeY−1)>>CtbLog2SizeY)−subpic_ctu_top_left_y[i]−1.         subpic_treated_as_pic_flag[i] equal to 1 specifies that the i-th         subpicture of each coded picture in the CLVS is treated as a         picture in the decoding process excluding in-loop filtering         operations. subpic_treated_as_pic_flag[i] equal to 0 specifies         that the i-th subpicture of each coded picture in the CLVS is         not treated as a picture in the decoding process excluding         in-loop filtering operations. When not present, the value of         subpic_treated_as_pic_flag[i] is inferred to be equal to         sps_independent_subpics_flag.         When subpic_treated_as_pic_flag[i] is equal to 1, it is a         requirement of bitstream conformance that all of the following         conditions are true for each output layer and its reference         layers in an OLS that includes the layer containing the i-th         subpicture as an output layer:     -   All pictures in the output layer and its reference layers shall         have the same value of pic_width_in_luma_samples and the same         value of pic_height_in_luma_samples.     -   All the SPSs referred to by the output layer and its reference         layers shall have the same value of sps_num_subpics_minus1 and         shall have the same values of subpic_ctu_top_left_x[j].         subpic_ctu_top_left_y[j], subpic_width_minus1[j],         subpic_height_minus1[j], and         loop_filter_across_subpic_enabled_flag[j], respectively, for         each value of j in the range of 0 to sps_num_subpics_minus1,         inclusive.     -   All pictures in each access unit in the output layer and its         reference layers shall have the same value of SubpicIdVal[j] for         each value of j in the range of 0 to sps_num_subpics_minus1,         inclusive.         loop_filter_across_subpic_enabled_flag[i] equal to 1 specifies         that in-loop filtering operations may be performed across the         boundaries of the i-th subpicture in each coded picture in the         CLVS.         loop_filter_across_subpic_enabled_flag[i] equal to 0 specifies         that in-loop filtering operations are not performed across the         boundaries of the i-th subpicture in each coded picture in the         CLVS. When not present, the value of         loop_filter_across_subpic_enabled_pic_flag[i] is inferred to be         equal to 1−sps_independent_subpics_flag.         It is a requirement of bitstream conformance that the shapes of         the subpictures shall be such that each subpicture, when         decoded, shall have its entire left boundary and entire top         boundary consisting of picture boundaries or consisting of         boundaries of previously decoded subpictures.         sps_subpic_id_len_minus1 plus 1 specifies the number of bits         used to represent the syntax element sps_subpic_id[i], the         syntax elements pps_subpic_id[i], when present, and the syntax         element slice_subpic_id, when present. The value of         sps_subpic_id_len_minus1 shall be in the range of 0 to 15,         inclusive. The value of 1<<(sps_subpic_id_len_minus1+1) shall be         greater than or equal to sps_num_subpics_minus1+1.         subpic_id_mapping_explicitly_signalled_flag equal to 1 specifies         that the subpicture II) mapping is explicitly signalled, either         in the SPS or in the PPSs referred to by coded pictures of the         CLVS.         subpic_id_mapping_explicitly_signalled_flag equal to 0 specifies         that the subpicture ID mapping is not explicitly signalled for         the CLVS. When not present, the value of         subpic_id_mapping_explicitly_signalled_flag is inferred to be         equal to 0.         subpic_id_mapping_in_sps_flag equal to 1 specifies that the         subpicture ID mapping is signalled in the SPS when         subpic_id_mapping_explicitly_signalled_flag is equal to 1.         subpic_id_mapping_in_sps_flag equal to 0 specifies that         subpicture ID mapping is signalled in the PPSs referred to by         coded pictures of the CLVS when         subpic_id_mapping_explicitly_signalled_flag is equal to 1.         sps_subpic_id[i] specifies the subpicture ID of the i-th         subpicture. The length of the sps_subpic_id[i] syntax element is         sps_subpic_id_len_minus1+1 bits.         bit_depth_minus8 specifies the bit depth of the samples of the         luma and chroma arrays. BitDepth, and the value of the luma and         chroma quantization parameter range offset, QpBdOffset, as         follows:

BitDepth=8+bit_depth_minus8  (45)

QpBdOffset=6*bit_depth_minus8  (46)

bit_depth_minus8 shall be in the range of 0 to 8, inclusive. sps_entropy_coding_sync_enabled_flag equal to 1 specifies that a specific synchronization process for context variables is invoked before decoding the CTU that includes the first CTB of a row of CTBs in each tile in each picture referring to the SPS, and a specific storage process for context variables is invoked after decoding the CTU that includes the first CTB of a row of CTBs in each tile in each picture referring to the SPS. sps_entropy_coding_sync_enabled_flag equal to 0 specifies that no specific synchronization process for context variables is required to be invoked before decoding the CTU that includes the first CTB of a row of CTBs in each tile in each picture referring to the SPS, and no specific storage process for context variables is required to be invoked after decoding the CTU that includes the first CTB of a row of CTBs in each tile in each picture referring to the SPS. sps_wpp_entry_point_offsets_present_flag equal to 1 specifies that signalling for entry point offsets for CTU rows may be present in the slice headers of pictures referring to the SPS when sps_entropy_coding_sync_enabled_flag is equal to 1. sps_wpp_entry_point_offsets_present_flag equal to 0 specifies that signalling for entry point offsets for CTU rows are not present in the slice headers of pictures referring to the SPS. When not present, the value of sps_wpp_entry_point_offsets_present_flag is inferred to be equal to 0. sps_weighted_pred_flag equal to 1 specifies that weighted prediction may be applied to P slices referring to the SPS. sps_weighted_pred_flag equal to 0 specifies that weighted prediction is not applied to P slices referring to the SPS. sps_weighted_bipred_flag equal to 1 specifies that explicit weighted prediction may be applied to B slices referring to the SPS. sps_weighted_bipred_flag equal to 0 specifies that explicit weighted prediction is not applied to B slices referring to the SPS. log2_max_pic_order_cnt_lsb_minus4 specifies the value of the variable MaxPicOrderCntLsb that is used in the decoding process for picture order count as follows:

MaxPicOrderCntLsb=2^((log2_max_pic_order_cnt_lsb_minus4+4))  (47)

The value of log2_max_pic_order_cnt_lsb_minus4 shall be in the range of 0 to 12, inclusive. sps_poc_msb_flag equal to 1 specifies that the ph_poc_msb_present_flag syntax element is present in PHs referring to the SPS. sps_poc_msb_flag equal to 0 specifies that the ph_poc_msb_present_flag syntax element is not present in PHs referring to the SPS. poc_msb_len_minus1 plus 1 specifics the length, in bits, of the poc_msb_val syntax elements, when present in the PHs referring to the SPS. The value of poc_msb_len_minus1 shall be in the range of 0 to 32−log2_max_pic_order_cnt_lsb_minus4−5, inclusive. num_extra_ph_bits_bytes specifies the number of bytes of extra bits in the PH syntax structure for coded pictures referring to the SPS. The value of num_extra_ph_bits_bytes shall be equal to 0 in bitstreams conforming to this version of this Specification. Although the value of num_extra_ph_bits_bytes is required to be equal to 0 in this version of this Specification, decoder conforming to this version of this Specification shall allow the value of num_extra_ph_bits_bytes equal to 1 or 2 to appear in the syntax. num_extra_sh_bits_bytes specifies the number of bytes of extra bits in the slice headers for coded pictures referring to the SPS. The value of num_extra_sh_bits_bytes shall be equal to 0 in bitstreams conforming to this version of this Specification. Although the value of num_extra_sh_bits_bytes is required to be equal to 0 in this version of this Specification, decoder conforming to this version of this Specification shall allow the value of num_extra_sh_bits_bytes equal to 1 or 2 to appear in the syntax. sps_sublayer_dpb_params_flag is used to control the presence of max_dec_pic_buffering_minus1[i], max_num_reorder_pics[i], and max_latency_increase_plus1[i] syntax elements in the dpb_parameters( ) syntax structure in the SPS. When not present, the value of sps_sub_dpb_params_info_present_flag is inferred to be equal to 0. long_term_ref_pics_flag equal to 0 specifies that no LTRP is used for inter prediction of any coded picture in the CLVS. long_term_ref_pics_flag equal to 1 specifies that LTRPs may be used for inter prediction of one or more coded pictures in the CLVS. inter_layer_ref_pics_present_flag equal to 0 specifies that no ILRP is used for inter prediction of any coded picture in the CLVS. inter_layer_ref_pic_flag equal to 1 specifies that ILRPs may be used for inter prediction of one or more coded pictures in the CLVS. When sps_video_parameter_set_id is equal to 0, the value of inter_layer_ref_pics_present_flag is inferred to be equal to 0. When vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1, the value of inter_layer_ref_pics_present_flag shall be equal to 0. [Ed. (YK): Check whether there is a better name for this syntax element.] sps_idr_rpl_present_flag equal to 1 specifies that reference picture list syntax elements are present in slice headers of IDR pictures. sps_idr_rpl_present_flag equal to 0 specifies that reference picture list syntax elements are not present in slice headers of IDR pictures. rpl1_same_as_rpl0_flag equal to 1 specifies that the syntax element num_ref_pic_lists_in_sps[1] and the syntax structure ref_pic_list_struct(1, rplsIdx) are not present and the following applies:

-   -   The value of num_ref_pic_lists_in_sps[1] is inferred to be equal         to the value of num_ref_pic_lists_in_sps[0].     -   The value of each of syntax elements in ref_pic_list_struct(1,         rplsIdx) is inferred to be equal to the value of corresponding         syntax element in ref_pic_list_struct(0, rplsIdx) for rplsIdx         ranging from 0 to num_ref_pic_lists_in_sps[0]−1.         num_ref_pic_lists_in_sps[i] specifies the number of the         ref_pic_list_struct(listIdx, rplsIdx) syntax structures with         listIdx equal to i included in the SPS. The value of         num_ref_pic_lists_in_sps[i] shall be in the range of 0 to 64,         inclusive.     -   NOTE 4—For each value of listIdx (equal to 0 or 1), a decoder         should allocate memory for a total number of         num_ref_pic_lists_in_sps[i]+1 ref_pic_list_struct(listIdx,         rplsIdx) syntax structures since there may be one         ref_pic_list_struct(listIdx, rplsIdx) syntax structure directly         signalled in the slice headers of a current picture.         gtbtt_dual_tree_intra_flag equal to 1 specifies that, for I         slices, each CTU is split into coding units with 64×64 luma         samples using an implicit quadtree split, and these coding units         are the root of two separate coding_tree syntax structure for         luma and chroma. gtbtt_dual_tree_intra_flag equal to 0 specifies         separate coding_tree syntax structure is not used for I slices.         When gtbtt_dual_tree_intra_flag is not present, it is inferred         to be equal to 0.         log2_min_luma_coding_block_size_minus2 plus 2 specifies the         minimum luma coding block size. The value range of         log2_min_luma_coding_block_size_minus2 shall be in the range of         0 to Min(4, sps_log2_ctu_size_minus5+3), inclusive.         The variables MinCbLog2SizeY. MinCbSizeY, IbcBufWidthY,         IbcBufWidthC and Vsize are derived as follows:

MinCbLog2SizeY=log2_min_luma_coding_block_size_minus2+2  (48)

MinCbSizeY=1<<MinCbLog2SizeY  (49)

IbcBufWidthY=256*128/CtbSizeY  (50)

IbcBufWidthC=IbcBufWidthY/SubWidthC  (51)

VSize=Min(64,CtbSizeY)  (52)

The value of MinCbSizeY shall less than or equal to VSize. The variables CtbWidthC and CtbHeightC, which specify the width and height, respectively, of the array for each chroma CTB, are derived as follows:

-   -   If chroma_format_idc is equal to 0 (monochrome) or         separate_colour_plane_flag is equal to 1, CtbWidthC and         CtbHeightC are both equal to 0.     -   Otherwise, CtbWidthC and CtbHeightC are derived as follows:

CtbWidthC=CtbSizeY/SubWidthC  (53)

CtbHeightC=CtbSizeY/SubHeightC  (54)

For log2BlockWidth ranging from 0 to 4 and for log2BlockHeight ranging from 0 to 4, inclusive, the up-right diagonal scan order army initialization process as specified in clause 6.5.2 is invoked with 1<<log2BlockWidth and 1<<log2BlockHeight as inputs, and the output is assigned to DiagScanOrder[log2BlockWidth][log2BlockHeight]. For log2BlockWidth ranging from 0 to 6 and for log2BlockHeight ranging from 0 to 6, inclusive, the horizontal and vertical traverse scan order army initialization process as specified in clause 6.5.3 is invoked with 1<<log2BlockWidth and 1<<log2BlockHeight as inputs, and the output is assigned to HorTravScanOrder[log2BlockWidth][log2BlockHeight] and VerTravScanOrder[log2BlockWidth][log2BlockHeight]. partition_constraints_override_enabled_flag equal to 1 specifies the presence of partition_constraints_override_flag in PHs referring to the SPS. partition_constraints_override_enabled_flag equal to 0 specifies the absence of partition_constraints_override_flag in PHs referring to the SPS. sps_log2_diff_min_qt_min_cb_intra_slice_luma specifies the default difference between the base 2 logarithm of the minimum size in luma samples of a luma leaf block resulting from quadtree splitting of a CTU and the base 2 logarithm of the minimum coding block size in luma samples for luma CUs in slices with slice_type equal to 2 (I) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default difference can be overridden by ph_log2_diff_min_qt_min_cb_luma present in PHs referring to the SPS. The value of sps_log2_diff_min_qt_min_cb_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. The base 2 logarithm of the minimum size in luma samples of a luma leaf block resulting from quadtree splitting of a CTU is derived as follows:

MinQtLog2SizeIntraY=sps_log2_diff_min_qt_min_cb_intra_slice_luma+MinCbLog2SizeY  (55)

sps_max_mtt_hierarchy_depth_intra_slice_luma specifies the default maximum hierarchy depth for coding units resulting from multi-type tree splitting of a quadtree leaf in slices with slice_type equal to 2 (I) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default maximum hierarchy depth can be overridden by ph_max_mtt_hierarchy_depth_intra_slice_luma present in PHs referring to the SPS. The value of sps_max_mtt_hierarchy_depth_intra_slice_luma shall be in the range of 0 to 2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive. sps_log2_diff_max_bt_min_qt_intra_slice_luma specifies the default difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a luma coding block that can be split using a binary split and the minimum size (width or height) in luma samples of a luma leaf block resulting from quadtree splitting of a CTU in slices with slice_type equal to 2 (I) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default difference can be overridden by ph_log2_diff_max_bt_min_qt_luma present in PHs referring to the SPS. The value of sps_log2_diff_max_bt_min_qt_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeIntraY, inclusive. When sps_log2_diff_max_bt_min_qt_intra_slice_luma is not present, the value of sps_log2_diff max_bt_min_qt_intra_slice_luma is inferred to be equal to 0. sps_log2_diff_max_tt_min_qt_intra_slice_luma specifies the default difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a luma coding block that can be split using a ternary split and the minimum size (width or height) in luma samples of a luma leaf block resulting from quadtree splitting of a CTU in slices with slice_type equal to 2 (I) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default difference can be overridden by ph_log2_diff_max_tt_min_qt_luma present in PHs referring to the SPS. The value of sps_log2_diff_max_tt_min_qt_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeIntraY, inclusive. When sps_log2_diff_max_tt_min_qt_intra_slice_luma is not present, the value of sps_log2_diff_max_tt_min_qt_intra_slice_luma is inferred to be equal to 0. sps_log2_diff_min_qt_min_cb_inter_slice specifies the default difference between the base 2 logarithm of the minimum size in luma samples of a luma leaf block resulting from quadtree splitting of a CTU and the base 2 logarithm of the minimum luma coding block size in luma samples for luma CUs in slices with slice_type equal to 0 (B) or 1 (P) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default difference can be overridden by ph_log2_diff_min_qt_min_cb_luma present in PHs referring to the SPS. The value of sps_log2_diff_min_qt_min_cb_inter_slice shall be in the range of 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. The base 2 logarithm of the minimum size in luma samples of a luma leaf block resulting from quadtree splitting of a CTU is derived as follows:

MinQtLog2SizeInterY=sps_log2_diff_min_qt_min_cb_inter_slice+MinCbLog2SizeY(56)

sps_max_mtt_hierarchy_depth_inter_slice specifies the default maximum hierarchy depth for coding units resulting from multi-type tree splitting of a quadtree leaf in slices with slice_type equal to 0 (B) or 1 (P) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default maximum hierarchy depth can be overridden by ph_max_mtt_hierarchy_depth_inter_slice present in PHs referring to the SPS. The value of sps_max_mtt_hierarchy_depth_inter_slice shall be in the range of 0 to 2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive. sps_log2_diff_max_bt_min_qt_inter_slice specifies the default difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a luma coding block that can be split using a binary split and the minimum size (width or height) in luma samples of a luma leaf block resulting from quadtree splitting of a CTU in slices with slice_type equal to 0 (B) or 1 (P) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default difference can be overridden by ph_log2_diff_max_bt_min_qt_luma present in PHs referring to the SPS. The value of sps_log2_diff_max_bt_min_qt_inter_slice shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeInterY, inclusive. When sps_log2_diff_max_bt_min_qt_inter_slice is not present, the value of sps_log2_diff_max_bt_min_qt_inter_slice is inferred to be equal to 0. sps_log2_diff_max_tt_min_qt_inter_slice specifies the default difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a luma coding block that can be split using a ternary split and the minimum size (width or height) in luma samples of a luma leaf block resulting from quadtree splitting of a CTU in slices with slice_type equal to 0 (B) or 1 (P) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default difference can be overridden by ph_log2_diff_max_tt_min_qt_luma present in PHs referring to the SPS. The value of sps_log2_diff_max_tt_min_qt_inter_slice shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeInterY, inclusive. When sps_log2_diff_max_tt_min_qt_inter_slice is not present, the value of sps_log2_diff_max_tt_min_qt_inter_slice is inferred to be equal to 0. sps_log2_diff_min_qt_min_cb_intra_slice_chroma specifies the default difference between the base 2 logarithm of the minimum size in luma samples of a chroma leaf block resulting from quadtree splitting of a chroma CTU with treeType equal to DUAL_TREE_CHROMA and the base 2 logarithm of the minimum coding block size in luma samples for chroma CUs with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default difference can be overridden by ph_log2_diff_min_qt_min_cb_chroma present in PHs referring to the SPS. The value of sps_log2_diff_min_qt_min_cb_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. When not present, the value of sps_log2_diff_min_qt_min_cb_intra_slice_chroma is inferred to be equal to 0. The base 2 logarithm of the minimum size in luma samples of a chroma leaf block resulting from quadtree splitting of a CTU with treeType equal to DUAL_TREE_CHROMA is derived as follows:

MinQtLog2SizeIntraC=sps_log2_diff_min_qt_min_cb_intra_slice_chroma+MinCbLog2SizeY  (57)

sps_max_mtt_hierarchy_depth_intra_slice_chroma specifies the default maximum hierarchy depth for chroma coding units resulting from multi-type tree splitting of a chroma quadtree leaf with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default maximum hierarchy depth can be overridden by ph_max_mtt_hierarchy_depth_chroma present in PHs referring to the SPS. The value of sps_max_mtt_hierarchy_depth_intra_slice_chroma shall be in the range of 0 to 2(CtbLog2SizeY−MinCbLog2SizeY), inclusive. When not present, the value of sps_max_mtt_hierarchy_depth_intra_slice_chroma is inferred to be equal to 0. sps_log2_diff_max_bt_min_qt_intra_slice_chroma specifies the default difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a chroma coding block that can be split using a binary split and the minimum size (width or height) in luma samples of a chroma leaf block resulting from quadtree splitting of a chroma CTU with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default difference can be overridden by ph_log2_diff_max_bt_min_qt_chroma present in PHs referring to the SPS. The value of sps_log2_diff_max_bt_min_qt_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeIntraC, inclusive. When sps_log2_diff_max_bt_min_qt_intra_slice_chroma is not present, the value of sps_log2_diff_max_bt_min_qt_intra_slice_chroma is inferred to be equal to 0. sps_log2_diff_max_tt_min_qt_intra_slice_chroma specifies the default difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a chroma coding block that can be split using a ternary split and the minimum size (width or height) in luma samples of a chroma leaf block resulting from quadtree splitting of a chroma CTU with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) referring to the SPS. When partition_constraints_override_enabled_flag is equal to 1, the default difference can be overridden by ph_log2_diff_max_tt_min_qt_chroma present in PHs referring to the SPS. The value of sps_log2_diff_max_tt_min_qt_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeIntraC, inclusive. When sps_log2_diff_max_tt_min_qt_intra_slice_chroma is not present, the value of sps_log2_diff_max_tt_min_qt_intra_slice_chroma is inferred to be equal to 0. sps_max_luma_transform_size_64_flag equal to 1 specifies that the maximum transform size in luma samples is equal to 64. sps_max_luma_transform_size_64_flag equal to 0 specifies that the maximum transform size in luma samples is equal to 32. When CtbSizeY is less than 64, the value of sps_max_luma_transform_size_64_flag shall be equal to 0. The variables MinTbLog2SizeY, MaxTbLog2SizeY, MinTbSizeY, and MaxTbSizeY are derived as follows:

MinTbLog2SizeY=2  (58)

MaxTbLog2SizeY=sps_max_luma_transform_size_64_flag?6:5  (59)

MinTbSizeY=1<<MinTbLog2SizeY  (60)

MaxTbSizeY=1<<MaxTbLog2SizeY  (61)

sps_joint_cbcr_enabled_flag equal to 0 specifies that the joint coding of chroma residuals is disabled. sps_joint_cbcr_enabled_flag equal to 1 specifies that the joint coding of chroma residuals is enabled. When not present, the value of sps_joint_cbcr_enabled_flag is inferred to be equal to 0. same_qp_table_for_chroma equal to 1 specifies that only one chroma QP mapping table is signalled and this table applies to Cb and Cr residuals and additionally to joint Cb-Cr residuals when sps_joint_cbcr_enabled_flag is equal to 1. same_qp_table_for_chroma equal to 0 specifies that chroma QP mapping tables, two for Cb and Cr, and one additional for joint Cb-Cr when sps_joint_cbcr_enabled_flag is equal to 1, are signalled in the SPS. When same_qp_table_for_chroma is not present in the bitstream, the value of same_qp_table_for_chroma is inferred to be equal to 1. qp_table_start_minus26[i] plus 26 specifies the starting luma and chroma QP used to describe the i-th chroma QP mapping table. The value of qp_table_start_minus26[i] shall be in the range of −26−QpBdOffset to 36 inclusive. When qp_table_start_minus26[i] is not present in the bitstream, the value of qp_table_start_minus26[i] is inferred to be equal to 0. num_points_in_qp_table_minus1[i] plus 1 specifies the number of points used to describe the i-th chroma QP mapping table. The value of num_points_in_qp_table_minus1[i] shall be in the range of 0 to 63+QpBdOffset, inclusive. When num_points_in_qp_table_minus1[0] is not present in the bitstream, the value of num_points_in_qp_table_minus1[0] is inferred to be equal to 0. delta_qp_in_val_minus1[i][j] specifies a delta value used to derive the input coordinate of the j-th pivot point of the i-th chroma QP mapping table. When delta_qp_in_val_minus1[0][j] is not present in the bitstream, the value of delta_qp_in_val_minus1[0][j] is inferred to be equal to 0. delta_qp_diff_val[i][j] specifies a delta value used to derive the output coordinate of the j-th pivot point of the i-th chroma QP mapping table. The i-th chroma QP mapping table ChromaQpTable[i] for i=0 . . . numQpTables−1 is derived as follows:

qpInVal[ i ][ 0 ] = qp_table_start_minus26[ i ] + 26 qpOutVal[ i ][ 0 ] = qpInVal[ i ][ 0 ] for( j = 0; j <= num_points_in_qp_table_minus1[ i ]; j++ ) {  qpInVal[ i ][ j + 1 ] = qpInVal[ i ][ j ] + delta_qp_in_val_minus1[  i ][ j ] + 1  qpOutVal[ i ][ j + 1 ] = qpOutVal[ i ][ j ] + ( delta_qp_in_val_minus1[ i ][ j ] {circumflex over ( )} delta_qp_diff_val[ i ][ j ] ) } ChromaQpTable[ i ][ qpInVal[ i ][ 0 ] ] = qpOutVal[ i ][ 0 ] for( k = qpInVal[ i ][ 0 ] − 1; k >= −QpBdOffset, k − − )  ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k + 1 ] − 1) (62) for( j = 0; j <= num_points_in_qp_table_minus1[ i ]; j++ ) {  sh = ( delta_qp_in_val_minus1[ i ][j ] + 1 ) >> 1  for( k = qpInVal[ i ][ j ] + 1, m = 1; k <= qpInval[ i ][ j + 1 ]; k++, m++ )   ChromaQpTable[ i ][ k ] = ChromaQpTable[ i ][ qpInVal[ i ][    j ] ] + ( ( qpOutVal[ i ][j + 1] − qpOutVal[ i ][j ] ) * m + sh ) / ( delta_qp_in_val_minus1[ i ][j] + 1 ) } for( k = qpInVal[ i ][ num_points_in_qp_table_minus1[ i ] + 1 ] + 1; k <= 63, k++ )  ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k − 1 ] + 1 ) When same_qp_table_for_chroma is equal to 1. ChromaQpTable[1][k] and ChromaQpTable[2][k] are set equal to ChromaQpTable[0][k] fork in the range of −QpBdOffset to 63, inclusive. It is a requirement of bitstream conformance that the values of qpinVal[i][j] and qpOutVal[i][j] shall be in the range of −QpBdOffset to 63, inclusive for i in the range of 0 to numQpTables−1, inclusive, and j in the range of 0 to num_points_in_qp_table_minus1[i]+1, inclusive. sps_sao_enabled_flag equal to 1 specifies that the sample adaptive offset process is applied to the reconstructed picture after the deblocking filter process. sps_sao_enabled_flag equal to 0 specifies that the sample adaptive offset process is not applied to the reconstructed picture after the deblocking filter process. sps_alf_enabled_flag equal to 0 specifies that the adaptive loop filter is disabled. sps_alf_enabled_flag equal to 1 specifies that the adaptive loop filter is enabled. sps_ccalf_enabled_flag equal to 0 specifies that the cross-component adaptive loop filter is disabled. sps_ccalf_enabled_flag equal to 1 specifies that the cross-component adaptive loop filter may be enabled. sps_transform_skip_enabled_flag equal to 1 specifies that transform_skip_flag may be present in the transform unit syntax. sps_transform_skip_enabled_flag equal to 0 specifies that transform_skip_flag is not present in the transform unit syntax. log2_transform_skip_max_size_minus2 specifies the maximum block size used for transform skip, and shall be in the range of 0 to 3, inclusive. The variable MaxTsSize is set equal to 1<<(log2_transform_skip_max_size_minus2+2). sps_bdpcm_enabled_flag equal to 1 specifies that intra_bdpcm_luma_flag and intra_bdpcm_chroma_flag may be present in the coding unit syntax for infra coding units. sps_bdpcm_enabled_flag equal to 0 specifies that intra_bdpcm_luma_flag and intra_bdpcm_chroma_flag are not present in the coding unit syntax for intra coding units. When not present, the value of sps_bdpcm_enabled_flag is inferred to be equal to 0. sps_ref_wraparound_enabled_flag equal to 1 specifies that horizontal wrap-around motion compensation is applied in inter prediction. sps_ref_wraparound_enabled_flag equal to 0 specifies that horizontal wrap-around motion compensation is not applied. When the value of (CtbSizeY/MinCbSizeY+1) is greater than (pic_width_in_luma_samples/MinCbSizeY−1), where pic_width_in_luma_samples is the value of pic_width_in_luma_samples in any PPS that refers to the SPS, the value of sps_ref_wraparound_enabled_flag shall be equal to 0. [Ed. (YK): The semantics here still depends on PPS syntax elements.] sps_temporal_mvp_enabled_flag equal to 1 specifies that temporal motion vector predictors may be used in the CLVS. sps_temporal_mvp_enabled_flag equal to 0 specifies that temporal motion vector predictors are not used in the CLVS. sps_sbtmvp_enabled_flag equal to 1 specifies that subblock-based temporal motion vector predictors may be used in decoding of pictures with all slices having slice_type not equal to 1 in the CLVS. sps_sbtmvp_enabled_flag equal to 0 specifies that subblock-based temporal motion vector predictors are not used in the CLVS. When sps_sbtmvp_enabled_flag is not present, it is inferred to be equal to 0. sps_amvr_enabled_flag equal to 1 specifies that adaptive motion vector difference resolution is used in motion vector coding. amvr_enabled_flag equal to 0 specifies that adaptive motion vector difference resolution is not used in motion vector coding. sps_bdof_enabled_flag equal to 0 specifies that the bi-directional optical flow inter prediction is disabled. sps_bdof_enabled_flag equal to 1 specifies that the bi-directional optical flow inter prediction is enabled. sps_bdof_pic_present_flag equal to 1 specifies that ph_disable_bdof_flag is present in PHs referring to the SPS. sps_bdof_pic_present_flag equal to 0 specifies that ph_disable_bdof_flag is not present in PHs referring to the SPS. When sps_bdof_pic_present_flag is not present, the value of sps_bdof_pic_present_flag is inferred to be equal to 0. sps_smvd_enabled_flag equal to 1 specifies that symmetric motion vector difference may be used in motion vector decoding. sps_smvd_enabled_flag equal to 0 specifies that symmetric motion vector difference is not used in motion vector coding. sps_dmvr_enabled_flag equal to 1 specifies that decoder motion vector refinement based inter bi-prediction is enabled. sps_dmvr_enabled_flag equal to 0 specifies that decoder motion vector refinement based inter bi-prediction is disabled. sps_dmvr_pic_present_flag equal to 1 specifies that ph_disable_dmvr_flag is present in PHs referring to the SPS. sps_dmvr_pic_present_flag equal to 0 specifies that ph_disable_dmvr_flag is not present in PHs referring to the SPS. When sps_dmvr_pic_present_flag is not present, the value of sps_dmvr_pic_present_flag is inferred to be equal to 0. sps_mmvd_enabled_flag equal to 1 specifies that merge mode with motion vector difference is enabled. sps_mmvd_enabled_flag equal to 0 specifies that merge mode with motion vector difference is disabled. sps_isp_enabled_flag equal to 1 specifies that intra prediction with subpartitions is enabled. sps_isp_enabled_flag equal to 0 specifies that intra prediction with subpartitions is disabled. sps_mrl_enabled_flag equal to 1 specifies that intra prediction with multiple reference lines is enabled. sps_mrl_enabled_flag equal to 0 specifies that intra prediction with multiple reference lines is disabled. sps_mip_enabled_flag equal to 1 specifies that matrix-based intra prediction is enabled. sps_mip_enabled_flag equal to 0 specifies that matrix-based infra prediction is disabled. sps_cclm_enabled_flag equal to 0 specifies that the cross-component linear model intra prediction from luma component to chroma component is disabled. sps_cclm_enabled_flag equal to 1 specifies that the cross-component linear model intra prediction from luma component to chroma component is enabled. When sps_cclm_enabled_flag is not present, it is inferred to be equal to 0. sps_chroma_horizontal_collocated_flag equal to 1 specifies that prediction processes operate in a manner designed for chroma sample positions that are not horizontally shifted relative to corresponding luma sample positions. sps_chroma_horizontal_collocated_flag equal to 0 specifies that prediction processes operate in a manner designed for chroma sample positions that are shifted to the right by 0.5 in units of luma samples relative to corresponding luma sample positions. When sps_chroma_horizontal_collocated_flag is not present, it is inferred to be equal to 1. sps_chroma_vertical_collocated_flag equal to 1 specifies that prediction processes operate in a manner designed for chroma sample positions that are not vertically shifted relative to corresponding luma sample positions. sps_chroma_vertical_collocated_flag equal to 0 specifies that prediction processes operate in a manner designed for chroma sample positions that are shifted downward by 0.5 in units of luma samples relative to corresponding luma sample positions. When sps_chroma_vertical_collocated_flag is not present, it is inferred to be equal to 1. sps_mts_enabled_flag equal to 1 specifies that sps_explicit_mts_intra_enabled_flag is present in the sequence parameter set RBSP syntax and sps_explicit_mts_inter_enabled_flag is present in the sequence parameter set RBSP syntax. sps_mts_enabled_flag equal to 0 specifies that sps_explicit_mts_intra_enabled_flag is not present in the sequence parameter set RBSP syntax and sps_explicit_mts_inter_enabled_flag is not present in the sequence parameter set RBSP syntax. sps_explicit_mts_intra_enabled_flag equal to 1 specifies that mts_idx may be present in intra coding unit syntax. sps_explicit_mts_intra_enabled_flag equal to 0 specifies that mts_idx is not present in intra coding unit syntax. When not present, the value of sps_explicit_mts_intra_enabled_flag is inferred to be equal to 0. sps_explicit_mts_inter_enabled_flag equal to 1 specifies that mts_idx may be present in inter coding unit syntax. sps_explicit_mts_inter_enabled_flag equal to 0 specifies that mts_idx is not present in inter coding unit syntax. When not present, the value of sps_explicit_mts_inter_enabled_flag is inferred to be equal to 0. six_minus_max_num_merge_cand specifies the maximum number of merging motion vector prediction (MVP) candidates supported in the SPS subtracted from 6. The value of six_minus_max_num_merge_cand shall be in the range of 0 to 5, inclusive. The maximum number of merging MVP candidates. MaxNumMergeCand, is derived as follows:

MaxNumMergeCand=6−six_minus_max_num_merge_cand  (63)

sps_sbt_enabled_flag_equal to 0 specifies that subblock transform for inter-predicted CUs is disabled. sps_sbt_enabled_flag equal to 1 specifies that subblock transform for inter-predicted CU is enabled. sps_affine_enabled_flag specifies whether affine model based motion compensation can be used for inter prediction. If sps_affine_enabled_flag is equal to 0, the syntax shall be constrained such that no affine model based motion compensation is used in the CLVS, and inter_affine_flag and cu_affine_type_flag are not present in coding unit syntax of the CLVS. Otherwise (sps_affine_enabled_flag is equal to 1), affine model based motion compensation can be used in the CLVS. five_minus_max_num_subblock_merge_cand specifies the maximum number of subblock-based merging motion vector prediction candidates supported in the SPS subtracted from 5. sps_affine_type_flag specifies whether 6-parameter affine model based motion compensation can be used for inter prediction. If sps_affine_type_flag is equal to 0, the syntax shall be constrained such that no 6-parameter affine model based motion compensation is used in the CLVS, and cu_affine_type_flag is not present in coding unit syntax in the CLVS. Otherwise (sps_affine_type_flag is equal to 1). 6-parameter affine model based motion compensation can be used in the CLVS. When not present, the value of sps_affine_type_flag is inferred to be equal to 0. sps_affine_amvr_enabled_flag equal to 1 specifies that adaptive motion vector difference resolution is used in motion vector coding of affine inter mode. sps_affine_amvr_enabled_flag equal to 0 specifies that adaptive motion vector difference resolution is not used in motion vector coding of affine inter mode. When not present, the value of sps_affine_amvr_enabled_flag is inferred to be equal to 0. sps_affine_prof_enabled_flag specifies whether the prediction refinement with optical flow can be used for affine motion compensation. If sps_affine_prof_enabled_flag is equal to 0, the affine motion compensation shall not be refined with optical flow. Otherwise (sps_affine_prof_enabled_flag is equal to 1), the affine motion compensation can be refined with optical flow. When not present, the value of sps_affine_prof_enabled_flag is inferred to be equal to 0. sps_prof_pic_present_flag equal to 1 specifies that ph_disable_prof_flag is present in PHs referring to the SPS. sps_prof pic present_flag equal to 0 specifies that ph_disable_prof flag is not present in PHs referring to the SPS. When sps_prof_pic_present_flag is not present, the value of sps_prof_pic_present_flag is inferred to be equal to 0. sps_palette_enabled_flag equal to 1 specifies that pred_mode_plt_flag may be present in the coding unit syntax. sps palette_enabled_flag equal to 0 specifies that pred_mode plt_flag is not present in the coding unit syntax. When sps_palette_enabled_flag is not present, it is inferred to be equal to 0. sps_act_enabled_flag equal to 1 specifies that adaptive colour transform may be used and the cu_act_enabled_flag may be present in the coding unit syntax. sps_act_enabled_flag equal to 0 speifies that adaptive colour transform is not used and cu_act_enabled_flag is not present in the coding unit syntax. When sps_act_enabled_flag is not present, it is inferred to be equal to 0. min_qp_prime_ts_minus4 specifies the minimum allowed quantization parameter for transform skip mode as follows:

QpPrimeTsMin=4+min_qp_prime_ts_minus4  (64)

The value of min_qp_prime_ts_minus4 shall be in the range of 0 to 48, inclusive. sps_bcw_enabled_flag specifies whether bi-prediction with CU weights can be used for inter prediction. if sps_bcw_enabled_flag is equal to 0, the syntax shall be constrained such that no bi-prediction with CU weights is used in the CLVS, and bcw_idx is not present in coding unit syntax of the CLVS. Otherwise (sps_bcw_enabled_flag is equal to 1), bi-prediction with CU weights can be used in the CLVS. sps_ibc_enabled_flag equal to 1 specifies that the IBC prediction mode may be used in decoding of pictures in the CLVS. sps_ibc_enabled_flag equal to 0 specifies that the IBC prediction mode is not used in the CLVS. When sps_ibc_enabled_flag is not present, it is inferred to be equal to 0. six_minus_max_num_ibc_merge cand specifies the maximum number of IBC merging block vector prediction (BVP) candidates supported in the SPS subtracted from 6. The value of six_minus_max_num ibc_merge_cand shall be in the range of 0 to 5, inclusive. The maximum number of IBC merging BVP candidates. MaxNumIbcMergeCand, is derived as follows:

if( sps_ibc_enabled_flag )  MaxNumIbcMergeCand = 6 − (65)  six_minus_max_num_ibc_merge_cand else  MaxNumIbcMergeCand = 0 sps_cup_enabled_flag specifies that ciip_flag may be present in the coding unit syntax for inter coding units. sps_ciip_enabled_flag equal to 0 specifies that ciip_flag is not present in the coding unit syntax for inter coding units. sps_fpel_mmvd_enabled_flag equal to 1 specifies that merge mode with motion vector difference is using integer sample precision. sps_fpel_mmvd_enabled_flag equal to 0 specifies that merge mode with motion vector difference can use fractional sample precision. sps_gpm_enabled_flag specifies whether geometric partition based motion compensation can be used for inter prediction. sps_gpm_enabled_flag equal to 0 specifies that the syntax shall be constrained such that no geometric partition based motion compensation is used in the CLVS, and merge_gpm_partition_idx, merge_gpm_idx0, and merge_gpm_idx1 are not present in coding unit syntax of the CLVS. sps_gpm_enabled_flag equal to 1 specifies that geometric partition based motion compensation can be used in the CLVS. When not present, the value of sps_gpm_enabled_flag is inferred to be equal to 0. max_num_merge_cand_minus_max_num_gpm_cand specifies the maximum number of geometric partitioning merge mode candidates supported in the SPS subtracted from MaxNumMergeCand. The maximum number of geometric partitioning merge mode candidates, MaxNumGpmMergeCand, is derived as follows:

if( sps_gpm_enabled_flag && MaxNumMergeCand >= 3 )  MaxNumGpmMergeCand = MaxNumMergeCand −   max_num_merge_cand_minus_max_num_gpm_cand (66) else if( sps_gpm_enabled_flag && MaxNumMergeCand = = 2 )  MaxNumMergeCand = 2 else  MaxNumGpmMergeCand = 0 The value of MaxNumGpmMergeCand shall be in the range of 2 to MaxNumMergeCand, inclusive. sps_lmcs_enabled_flag equal to 1 specifies that luma mapping with chroma scaling is used in the CLVS. sps_lmcs_enabled_flag equal to 0 specifies that luma mapping with chroma scaling is not used in the CLVS. sps_lfnst_enabled_flag equal to 1 specifies that lfnst_idx may be present in intra coding unit syntax. sps_lfnst_enabled_flag equal to 0 specifies that lfnst_idx is not present in intra coding unit syntax. sps_ladf_enabled_flag equal to 1, specifies that sps_num_ladf_intervals_minus2, sps_ladf_lowest_interval_qp_offset, sps_ladf_qp_offset[i], and sps_ladf_delta_threshold_minus1[i] are present in the SPS. sps_num_ladf_intervals_minus2 plus 1 specifies the number of sps_ladf_delta_threshold_minus1[i] and sps_ladf_qp_offset[i] syntax elements that are present in the SPS. The value of sps_num_ladf_intervals_minus2 shall be in the range of 0 to 3, inclusive. sps_ladf_lowest_interval_qp_offset specifies the offset used to derive the variable qP as specified in clause 8.8.3.6.1. The value of sps_ladf_lowest_interval_qp_offset shall be in the range of −63 to 63, inclusive. sps_ladf_qp_offset[i] specifies the offset array used to derive the variable qP as specified in clause 8.8.3.6.1. The value of sps_ladf_qp_offset[i] shall be in the range of −63 to 63, inclusive. sps_ladf_delta_threshold_minus1[i] is used to compute the values of SpsLadfIntervalLowerBound[i], which specifies the lower bound of the i-th luma intensity level interval. The value of sps_ladf_delta_threshold_minus1[i] shall be in the range of 0 to 2^(BitDepth)−3, inclusive. The value of SpsLadfIntervalLowerBound[0] is set equal to 0. For each value of i in the range of 0 to sps_num_ladf_intervals_minus2, inclusive, the variable SpsLadfIntervalLowerBound[i+1] is derived as follows:

SpsLadfIntervalLowerBound[i+1]=SpsLadfIntervalLowerBound[i]+sps_ladf_delta_threshold_minus1[i]+1  (67)

log2_parallel_merge_level_minus2 plus 2 specifies the value of the variable Log2ParMrgLevel, which is used in the derivation process for spatial merging candidates as specified in clause 8.5.2.3, the derivation process for motion vectors and reference indices in subblock merge mode as specified in clause 8.5.5.2, and to control the invocation of the updating process for the history-based motion vector predictor list in clause 8.5.2.1. The value of log2_parallel_merge_level_minus2 shall be in the range of 0 to CtbLog2SizeY−2, inclusive. The variable Log2ParMrgLevel is derived as follows:

Log2ParMrgLevel=log2_parallel_merge_level_minus2+2  (68)

sps_scaling_list_enabled_flag equal to 1 specifies that a scaling list is used for the scaling process for transform coefficients. sps_scaling_list_enabled_flag equal to 0 specifies that scaling list is not used for the scaling process for transform coefficients. sps_dep_quant_enabled_flag equal to 0 specifies that dependent quantization is disabled for pictures referring to the SPS. sps_dep_quant_enabled_flag equal to 1 specifies that dependent quantization may be enabled for pictures referring to the SPS. sps_sign_data_hiding_enabled_flag equal to 0 specifies that sign bit hiding is disabled for pictures referring to the SPS. sps_sign_data_hiding_enabled_flag equal to 1 specifies that sign bit hiding may be enabled for pictures referring to the SPS. When sps_sign_data_hiding_enabled_flag is not present, it is inferred to be equal to 0. sps_virtual_boundaries_enabled_flag equal to 1 specifies that disabling in-loop filtering across virtual boundaries may be applied in the coded pictures in the CLVS. sps_virtual_boundaries_enabled_flag equal to 0 specifies that disabling in-loop filtering across virtual boundaries is not applied in the coded pictures in the CLVS. In-loop filtering operations include the deblocking filter, sample adaptive offset filter, and adaptive loop filter operations. sps_virtual_boundaries_present_flag equal to 1 specifies that information of virtual boundaries is signalled in the SPS. sps_virtual_boundaries_present_flag equal to 0 specifies that information of virtual boundaries is not signalled in the SPS. When there is one or more than one virtual boundaries signalled in the SPS, the in-loop filtering operations are disabled across the virtual boundaries in pictures referring to the SPS. In-loop filtering operations include the deblocking filter. sample adaptive offset filter, and adaptive loop filter operations. It is a requirement of bitstream conformance that when the value of res_change_in_clvs_allowed_flag is equal to 1, the value of sps_virtual_boundaries_present_flag shall be equal to 0. sps_num_ver_virtual_boundaries specifies the number of sps_virtual_boundaries_pos_x[i] syntax elements that are present in the SPS. When sps_num_ver_virtual_boundaries is not present, it is inferred to be equal to 0. sps_virtual_boundaries_pos_x[i] specifies the location of the i-th vertical virtual boundary in units of luma samples divided by 8. The value of sps_virtual_boundaries_pos_x[i] shall be in the range of 1 to Ceil(pic_width_in_luma_samples+8)−1, inclusive. [Ed. (VD): pic_width_in_luma_samples is in the PPS, not in the SPS.] sps_num_hor_virtual_boundaries specifies the number of sps_virtual_boundaries_pos_y[i] syntax elements that are present in the SPS. When sps_num_hor_virtual_boundaries is not present, it is inferred to be equal to 0. When sps_virtual_boundaries_enabled_flag is equal to 1 and sps_virtual_boundaries_present_flag is equal to 1, the sum of sps_num_ver_virtual_bouudaries and sps_num_hor_virtual_boundaries shall be greater than 0. sps_virtual_boundaries_pos_y[i] specifies the location of the i-th horizontal victual boundary in units of luma samples divided by 8. The value of sps_virtual_boundaries_pos_y[i] shall be in the range of 1 to Ceil(pic_height_in_luma_samples+8)−1, inclusive. [Ed. (VD): pic_height_in_luma_samples is in the PPS, not in the SPS.] sps_general_hrd_params_present_flag equal to 1 specifies that the syntax structure general_hrd_parameters( ) is present in the SPS RBSP syntax structure. sps_general_hrd_params_present_flag equal to 0 specifies that the syntax structure general_hrd_parameters( ) is not present in the SPS RBSP syntax structure. sps_sublayer_cpb_params_present_flag equal to 1 specifies that the syntax structure old_hrd_parameters( ) in the SPS RBSP includes HRD parameters for sublayer representations with TemporalId in the range of 0 to sps_max_sublayers_minus1, inclusive. sps_sublayer_cpb_params_present_flag equal to 0 specifies that the syntax structure ols_hrd_parameters( ) in the SPS RBSP includes HRD parameters for the sublayer representation with TemporalId equal to sps_max_sublayers_minus1 only. When sps_max_sublayers_minus1 is equal to 0, the value of sps_sublayer_cpb_params_present_flag is inferred to be equal to 0. When sps_sublayer_cpb_params_present_flag is equal to 0, the HRD parameters for the sublayer representations with TemporalId in the range of 0 to sps_max_sublayers_minus1−1, inclusive, are inferred to be the same as that for the sublayer representation with TemporalId equal to sps_max_sublayers_minus1. These include the HRD parameters starting from the fixed_pic_rate_general_flag[i] syntax element till the sublayer_hrd_parameters(i) syntax structure immediately under the condition “if(general_vcl_hrd_params_present_flag)” in the ols_hrd_parameters syntax structure. field_seq_flag equal to 1 indicates that the CLVS conveys pictures that represent fields. field_seq_flag equal to 0 indicates that the CLVS conveys pictures that represent frames. When general_frame_only_constraint_flag is equal to 1, the value of field_seq_flag shall be equal to 0. When field_seq_flag is equal to 1, a frame-field information SEI message shall be present for every coded picture in the CLVS.

-   -   NOTE 5—The specified decoding process does not treat pictures         that represent fields or frames differently. A sequence of         pictures that represent fields would therefore be coded with the         picture dimensions of an individual field. For example, pictures         that represent 1080i fields would commonly have cropped output         dimensions of 1920×540. while the sequence picture rate would         commonly express the rate of the source fields (typically         between 50 and 60 Hz), instead of the source frame rate         (typically between 25 and 30 Hz).         vui_parameters_present_flag equal to 1 specifies that the syntax         structure vui_parameters( ) is present in the SPS RBSP syntax         structure. vui_parameters_present_flag equal to 0 specifies that         the syntax structure vui_parameters( ) is not present in the SPS         RBSP syntax structure.         sps_extension_flag equal to 0 specifies that no         sps_extension_data_flag syntax elements are present in the SPS         RBSP syntax structure. sps_extension_flag equal to 1 specifies         that there are sps_extension_data_flag syntax elements present         in the SPS RBSP syntax structure.         sps_extension_data_flag may have any value. Its presence and         value do not affect decoder conformance to profiles specified in         this version of this Specification. Decoders conforming to this         version of this Specification shall ignore all         sps_extension_data_flag syntax elements.

3.6. PPS Syntax and Semantics

In the latest WC draft text, the PPS syntax and semantics are as follows:

Descriptor pic_parameter_set_rbsp( ) {  pps_pic_parameter_set_id ue(v)  pps_seq_parameter_set_id u(4)  mixed_nalu_types_in_pic_flag u(1)  pic_width_in_luma_samples ue(v)  pic_height_in_luma_samples ue(v)  pps_conformance_window_flag u(1)  if( pps_conformance_window_flag ) {   pps_conf_win_left_offset ue(v)   pps_conf_win_right_offset ue(v)   pps_conf_win_top_offset ue(v)   pps_conf_win_bottom_offset ue(v)  }  scaling_window_explicit_signalling_flag u(1)  if( scaling_window_explicit_signalling_flag ) {   scaling_win_left_offset ue(v)   scaling_win_right_offset ue(v)   scaling_win_top_offset ue(v)   scaling_win_bottom_offset ue(v)  }  output_flag_present_flag u(1)  subpic_id_mapping_in_pps_flag u(1)  if( subpic_id_mapping_in_pps_flag ) {   pps_num_subpics_minus1 ue(v)   pps_subpic_id_len_minus1 ue(v)   for( i = 0; i <= pps_num_subpic_minus1; i++ )    pps_subpic_id[ i ] u(v)  }  no_pic_partition_flag u(1)  if( !no_pic_partition_flag ) {   pps_log2_ctu_size_minus5 u(2)   num_exp_tile_columns_minus1 ue(v)   num_exp_tile_rows_minus1 ue(v)   for( i = 0; i <= num_exp_tile_columns_minus1; i++ )    tile_column_width_minus1[ i ] ue(v)   for( i = 0; i <= num_exp_tile_rows_minus1; i++ )    tile_row_height_minus1[ i ] ue(v)   if( NumTilesInPic > 1 )    rect_slice_flag u(1)   if( rect_slice_flag )    single_slice_per_subpic_flag u(1)   if( rect_slice_flag &&   !single_slice_per_subpic_flag ) {    num_slices_in_pic_minus1 ue(v)    if( num_slices_in_pic_minus1 > 0 )     tile_idx_delta_present_flag u(1)    for( i = 0; i < num_slices_in_pic_minus1; i++ ) {     if( NumTileColumns > 1 )      slice_width_in_tiles_minus1[ i ] ue(v)     if( NumTileRows > 1 &&       ( tile_idx_delta_present_flag || tileIdx %       NumTileColumns = = 0 ) )      slice_height_in_tiles_minus1[ i ] ue(v)     if( slice_width_in_tiles_minus1[ i ] = = 0 &&       slice_height_in_tiles_minus1[ i ] = = 0 &&       RowHeight[ SliceTopLeftTileIdx[ i ] /       NumTileColumns ] > 1 ) {      num_exp_slices_in_tile[ i ] ue(v)      for( j = 0; j < num_exp_slices_in_tile[ i ];       j++ )       exp_slice_height_in_ctus_minus1[ j ] ue(v)      i += NumSlicesInTile[ i ] − 1     }     if( tile_idx_delta_present_flag && i <     num_slices_in_pic_minus1 )      tile_idx_delta[ i ] se(v)    }   }   loop_filter_across_tiles_enabled_flag u(1)   loop_filter_across_slices_enabled_flag u(1)  }  cabac_init_present_flag u(1)  for( i = 0; i < 2; i++ )   num_ref_idx_default_active_minus1[ i ] ue(v)  rpl1_idx_present_flag u(1)  init_qp_minus26 se(v)  cu_qp_delta_enabled_flag u(1)  pps_chroma_tool_offsets_present_flag u(1)  if( pps_chroma_tool_offsets_present_flag ) {   pps_cb_qp_offset se(v)   pps_cr_qp_offset se(v)   pps_joint_cbcr_qp_offset_present_flag u(1)   if( pps_joint_cbcr_qp_offset_present_flag )    pps_joint_cbcr_qp_offset_value se(v)   pps_slice_chroma_qp_offsets_present_flag u(1)   pps_cu_chroma_qp_offset_list_enabled_flag u(1)  }  if( pps_cu_chroma_qp_offset_list_enabled_flag ) {   chroma_qp_offset_list_len_minus1 ue(v)   for( i = 0; i <= chroma_qp_offset_list_len_minus1;   i++ ) {    cb_qp_offset_list[ i ] se(v)    cr_qp_offset_list[ i ] se(v)    if( pps_joint_cbcr_qp_offset_present_flag )     joint_cbcr_qp_offset_list[ i ] se(v)   }  }  pps_weighted_pred_flag u(1)  pps_weighted_bipred_flag u(1)  deblocking_filter_control_present_flag u(1)  if( deblocking_filter_control_present_flag ) {   deblocking_filter_override_enabled_flag u(1)   pps_deblocking_filter_disabled_flag u(1)   if( !pps_deblocking_filter_disabled_flag ) {    pps_beta_offset_div2 se(v)    pps_tc_offset_div2 se(v)    pps_cb_beta_offset_div2 se(v)    pps_cb_tc_offset_div2 se(v)    pps_cr_beta_offset_div2 se(v)    pps_cr_tc_offset_div2 se(v)   }  }  rpl_info_in_ph_flag u(1)  if( deblocking_filter_override_enabled_flag )   dbf_info_in_ph_flag u(1)  sao_info_in_ph_flag u(1)  alf_info_in_ph_flag u(1)  if( ( pps_weighted_pred_flag | |  pps_weighted_bipred_flag ) && rpl_info_in_ph_flag )   wp_info_in_ph_flag u(1)  qp_delta_info_in_ph_flag u(1)  pps_ref_wraparound_enabled_flag u(1)  if( pps_ref_wraparound_enabled_flag )   pps_ref_wraparound_offset ue(v)  picture_header_extension_present_flag u(1)  slice_header_extension_present_flag u(1)  pps_extension_flag u(1)  if( pps_extension_flag )   while( more_rbsp_data( ) )    pps_extension_data_flag u(1)  rbsp_trailing_bits( ) } A PPS RBSP shall be available to the decoding process prior to it being referenced, included in at least one AU with TemporalId less than or equal to the TemporalId of the PPS NAL unit or provided through external means. All PPS NAL units with a particular value of pps_pic_parameter_set_id within a PU shall have the same content. pps_pic_parameter_set_id identifies the PPS for reference by other syntax elements. The value of pps_pic_parameter_set_id shall be in the range of 0 to 63, inclusive. PPS NAL units. regardless of the nuh_layer_id values, share the same value space of pps_pic_parameter_set_id. Let ppsLayerId be the value of the nuh_layer_id of a particular PPS NAL unit, and vclLayerId be the value of the nuh_layer_id of a particular VCL NAL unit. The particular VCL NAL unit shall not refer to the particular PPS NAL unit unless ppsLayerId is less than or equal to vclLayerId and the layer with nuh_layer_id equal to ppsLayerId is included in at least one OLS that includes the layer with nuh_layer_id equal to vclLayerId. pps_seq_parameter_set_id specifies the value of sps_seq_parameter_set_id for the SPS. The value of pps_seq_parameter_set_id shall be in the range of 0 to 15, inclusive. The value of pps_seq_parameter_set_id shall be the same in all PPSs that are referred to by coded pictures in a CLVS. mixed_nalu_types_in_pic_flag equal to 1 specifies that each picture referring to the PPS has more than one VCL NAL unit, the VCL NAL units do not have the same value of nal_unit_type, and the picture is not an IRAP picture. mixed_nalu_types_in_pic_flag equal to 0 specifies that each picture referring to the PPS has one or more VCL NAL units and the VCL NAL units of each picture referring to the PPS have the same value of nal_unit_type. When no_mixed_nalu_types_in_pic_constraint_flag is equal to 1, the value of mixed_nalu_types_in_pic_flag shall be equal to 0. For each slice with a nal_unit_type value nalUnitTypeA in the range of IDR_W_RADL to CRA_NUT, inclusive. in a picture picA that also contains one or more slices with another value of nal_unit_type (i.e., the value of mixed_nalu_types_in_pic_flag for the picture picA is equal to 1), the following applies:

-   -   The slice shall belong to a subpicture subpicA for which the         value of the corresponding subpic_treated_as_pic_flag[i] is         equal to 1.     -   The slice shall not belong to a subpicture of picA containing         VCL NAL units with nal_unit_type not equal to nalUnitTypeA.     -   If nalUnitTypeA is equal to CRA, for all the following PUs         following the current picture in the CLVS in decoding order and         in output order, neither RefPicList[0] nor RefPicList[1] of a         slice in subpicA in those PUs shall include any picture         preceding picA in decoding order in an active entry.     -   Otherwise (i.e., nalUnitTypeA is equal to IDR_W_RADL or         IDR_N_LP), for all the PUs in the CLVS following the current         picture in decoding order, neither RefPicList[0] nor         RefPicList[1] of a slice in subpicA in those PUs shall include         any picture preceding picA in decoding order in an active entry.         -   NOTE 1—mixed_nalu_types_in_pic_flag equal to 1 indicates             that pictures referring to the PPS contain slices with             different NAL unit types. e.g., coded pictures originating             from a subpicture bitstream merging operation for which             encoders have to ensure matching bitstream structure and             further alignment of parameters of the original bitstreams.             One example of such alignments is as follows: When the value             of sps_idr_rpl_flag is equal to 0 and             mixed_nalu_types_in_pic_flag is equal to 1, a picture             referring to the PPS cannot have slices with nal_unit_type             equal to IDR_W_RADL or IDR_N_LP.             pic_width_in_luma_samples specifies the width of each             decoded picture referring to the PPS in units of luma             samples. pic_width_in_luma_samples shall not be equal to 0,             shall be an integer multiple of Max(8, MinCbSizeY), and             shall be less than or equal to             pic_width_max_in_luma_samples.             When res_change_in_clvs_allowed_flag equal to 0, the value             of pic_width_in_luma_samples shall be equal to             pic_width_max_in_luma_samples.             pic_height_in_luma_samples specifies the height of each             decoded picture referring to the PPS in units of luma             samples. pic_height_in_luma_samples shall not be equal to 0             and shall be an integer multiple of Max(8, MinCbSizeY), and             shall be less than or equal to             pic_height_max_in_luma_samples.             When res_change_in_clvs_allowed_flag equal to 0, the value             of pic_height_in_luma_samples shall be equal to             pic_height_max_in_luma_samples.             The variables PicWidthInCtbsY, PicHeightInCtbsY,             PicSizeInCtbsY, PicWidthInMinCbsY, PicHeightInMinCbsY,             PicSizeInMinCbsY, PicSizeInSamplesY, PicWidthInSamplesC and             PicHeightInLSamplesC are derived as follows:

PicWidthInCtbsY=Ceil(pic_width_in_luma_samples:CtbSizeY)  (69)

PicHeightInCtbsY=Ceil(pic_height_in_luma_samples+CtbSizeY)  (70)

PicSizeInCtbsY=PicWidthInCtbsY*PicHeightInCtbsY  (71)

PicWidthInMinCbsY=pic_width_in_luma_samples/MinCbSizeY  (72)

PicHeightInMinCbsY=pic_height_in_luma_samples/MinCbSizeY  (73)

PicSizeInMinCbsY=PicWidthInMinCbsY*PicHeightInMinCbsY  (74)

PicSizeInSamplesY=pic_width_in_luma_samples*pic_height_in_luma_samples  (75)

PicWidthInSamplesC=pic_width_in_luma_samples/SubWidthC  (76)

PicHeightInSamplesC=pic_height_in_luma_samples/SubHeightC  (77)

pps_conformance_window_flag equal to 1 indicates that the conformance cropping window offset parameters follow next in the PPS. pps_conformance_window_flag equal to 0 indicates that the conformance cropping window offset parameters are not present in the PPS. pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset specify the samples of the pictures in the CLVS that are output from the decoding process, in terms of a rectangular region specified in picture coordinates for output. When pps_conformance_window_flag is equal to 0, the values of pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset are inferred to be equal to 0. The conformance cropping window contains the luma samples with horizontal picture coordinates from SubWidthC*pps_conf_win_left_offset to pic_width_in_luma_samples−(SubWidthC*pps_conf_win_right_offset+1) and vertical picture coordinates from SubHeightC*pps_conf_win_top_offset to pic_height_in_luma_samples−(SubHeightC*pps_conf_win_bottom_offset+1), inclusive. The value of SubWidthC*(pps_conf_win_left_offset+pps_conf_win_right_offset) shall be less than pic_width_in_luma_samples, and the value of SubHeightC*(pps_conf_win_top_offset+pps_conf_win_bottom_offset) shall be less than pic_height_in_luma_samples. When ChromaArrayType is not equal to 0, the corresponding specified samples of the two chroma arrays are the samples having picture coordinates (x/SubWidthC, y/SubHeightC), where (x, y) are the picture coordinates of the specified luma samples.

-   -   NOTE 2—The conformance cropping window offset parameters are         only applied at the output. All internal decoding processes are         applied to the uncropped picture size.         Let ppsA and ppsB be any two PPSs referring to the same SPS. It         is a requirement of bitstream conformance that, when ppsA and         ppsB have the same the values of pic_width_in_luma_samples and         pic_height_in_luma_samples, respectively, ppsA and ppsB shall         have the same values of pps_conf_win_left_offset,         pps_conf_win_right_offset, pps_conf_win_top_offset, and         pps_conf_win_bottom_offset, respectively.         When pic_width_in_luma_samples is equal to         pic_width_max_in_luma_samples and pic_height_in_luma_samples is         equal to pic_height_max_in_luma_samples, it is a requirement of         bitstream conformance that pps_conf_win_left_offset,         pps_conf_win_right_offset, pps_conf_win_top_offset, and         pps_conf_win_bottom_offset, are equal to         sps_conf_win_left_offset, sps_conf_win_right_offset,         sps_conf_win_top_offset, and sps_conf_win_bottom offset,         respectively.         scaling_window_explicit_signalling_flag equal to 1 specifies         that the scaling window offset parameters are present in the         PPS. scaling_window_explicit_signalling_flag equal to 0         specifies that the scaling window offset parameters are not         present in the PPS. When res_change_in_clvs_allowed_flag is         equal to 0, the value of scaling_window_explicit_signalling_flag         shall be equal to 0.         scaling_win_left_ofset, scaling_win_right_offset,         scaling_win_top_offset, and scaling_win_bottom_offset specify         the offsets that are applied to the picture size for scaling         ratio calculation. When not present, the values of         scaling_win_left_offset, scaling_win_right_offset,         scaling_win_top_offset, and scaling_win_bottom_offset are         inferred to be equal to pps_conf_win_left_offset.         pps_conf_win_right_offset, pps_conf_win_top_offset, and         pps_conf_win_bottom_offset, respectively.         The value of         SubWidthC*(scaling_win_left_offset+scaling_win_right_offset)         shall be less than pic_width_in_luma_samples, and the value of         SubHeightC*(scaling_win_top_offset+scaling_win_bottom_offset)         shall be less than pic_height_in_luma_samples.

The variables PicOutputWidthL and PicOutputHeightL are derived as follows:

PicOutputWidthL=pic_width_in_luma_samples−SubWidthC*(scaling_win_right_offset+scaling_win_left_offset)  (78)

PicOutputHeightL=pic_height_in_luma_samples−SubWidthC*(scaling_win_bottom_offset+scaling_win_top_offset)  (79)

Let refPicOutputWidthL and refPicOutputHeightL be the PicOutputWidthL and PicOutputHeightL, respectively, of a reference picture of a current picture referring to this PPS. Is a requirement of bitstream conformance that all of the following conditions are satisfied:

-   -   PicOutputWidthL*2 shall be greater than or equal to         refPicWidthInLumaSamples.     -   PicOutputHeightL*2 shall be greater than or equal to         refPicHeightInLumaSamples.     -   PicOutputWidthL shall be less than or equal to         refPicWidthInLumaSamples*8.     -   PicOutputHeightL shall be less than or equal to         refPicHeightInLumaSamples*8.     -   PicOutputWidthL*pic_width_max_in_luma_samples shall be greater         than or equal to         refPicOutputWidthL*(pic_width_in_luma_samples−Max(8,         MinCbSizeY)).     -   PicOutputHeightL*pic_height_max_in_luma_samples shall be greater         than or equal to         refPicOutputHeightL*(pic_height_in_luma_samples−Max(8,         MinCbSizeY)).         output_flag_present_flag equal to 1 indicates that the         pic_output_flag syntax element is present in slice headers         referring to the PPS. output_flag_present_flag equal to 0         indicates that the pic_output_flag syntax element is not present         in slice headers referring to the PPS.         subpic_id_mapping_in_pps_flag equal to 1 specifies that the         subpicture ID mapping is signalled in the PPS.         subpic_id_mapping_in_pps_flag equal to 0 specifies that the         subpicture ID mapping is not signalled in the PPS. If         subpic_id_mapping_explicitly_signalled_flag is 0 or         subpic_id_mapping_in_sps_flag is equal to 1, the value of         subpic_id_mapping_in_pps_flag shall be equal to 0. Otherwise         (subpic_id_mapping_explicitly_signalled_flag is equal to 1 and         subpic_id_mapping_in_sps_flag is equal to 0), the value of         subpic_id_mapping_in_pps_flag shall be equal to 1.         pps_num_subpics_minus1 shall be equal to sps_num_subpics_minus1.         pps_subpic_id_len_minus1 shall be equal to         sps_subpic_id_len_minus1.         pps_subpic_id[i] specifies the subpicture ID of the i-th         subpicture. The length of the pps_subpic_id[i] syntax element is         pps_subpic_id_len_minus1+1 bits.         The variable SubpicIdVal[i], for each value of i in the range of         0 to sps_num_subpics_minus1, inclusive, is derived as follows:

for( i = 0; i <= sps_num_subpics_minus1; i++ )  if( subpic_id_mapping_explicitly_signalled_flag )   SubpicIdVal[ i ] = subpic_id_mapping_in_pps_flag ?   pps_subpic_id[ i ] : sps_subpic_id[ j ] (80)  else   SubpicIdVal[ i ] = i It is a requirement of bitstream conformance that both of the following constraints apply:

-   -   For any two different values of i and j in the range of 0 to         sps_num_subpics_minus1, inclusive, SubpicIdVal[i] shall not be         equal to SubpicIdVal[j].     -   When the current picture is not the first picture of the CLVS,         for each value of i in the range of 0 to sps_num_subpics_minus1,         inclusive, if the value of SubpicIdVal[i] is not equal to the         value of SubpicIdVal[i] of the previous picture in decoding         order in the same layer, the nal_unit_type for all coded slice         NAL units of the subpicture in the current picture with         subpicture index i shall be equal to a particular value in the         range of IDR_W_RADL to CRA_NUT, inclusive.         no_pic_partition_flag equal to 1 specifies that no picture         partitioning is applied to each picture referring to the PPS.         no_pic_partition_flag equal to 0 specifies each picture         referring to the PPS may be partitioned into more than one tile         or slice.         It is a requirement of bitstream conformance that the value of         no_pic_partition_flag shall be the same for all PPSs that are         referred to by coded pictures within a CLVS.         It is a requirement of bitstream conformance that the value of         no_pic_partition_flag shall not be equal to 1 when the value of         sps_num_subpics_minus1+1 is greater than 1.         pps_log2_ctu_size_minus5 plus 5 specifies the luma coding tree         block size of each CTU. pps_log2_ctu_size_minus5 shall be equal         to sps_log2_ctu_size_minus5.         num_exp_tile_columns_minus1 plus 1 specifies the number of         explicitly provided tile column widths. The value of         num_exp_tile_columns_minus1 shall be in the range of 0 to         PicWidthInCtbsY−1, inclusive. When no_pic_partition_flag is         equal to 1, the value of num_exp_tile_columns_minus1 is inferred         to be equal to 0.         num_exp_tile_rows_minus1 plus 1 specifies the number of         explicitly provided tile row heights. The value of         num_exp_tile_rows_minus1 shall be in the range of 0 to         PicHeightInCtbsY−1, inclusive. When no_pic_partition_flag is         equal to 1, the value of num_tile_rows_minus1 is inferred to be         equal to 0.         tile_column_width_minus1[i] plus 1 specifies the width of the         i-th tile column in units of CTBs for i in the range of 0 to         num_exp_tile_columns_minus1−1, inclusive.         tile_column_width_minus1[num_exp_tile_columns_minus1] is used to         derive the width of the tile columns with index greater than or         equal to num_exp_tile_columns_minus1 as specified in clause         6.5.1. The value of tile_column_width_minus1[i] shall be in the         range of 0 to PicWidthInCtbsY−1, inclusive. When not present,         the value of tile_column_width_minus1[0] is inferred to be equal         to PicWidthInCtbsY−1.         tile_row_height_minus1[i] plus 1 specifies the height of the         i-th tile row in units of CTBs for i in the range of 0 to         num_exp_tile_rows_minus1−1, inclusive.         tile_row_height_minus1[num_exp_tile_rows_minus1] is used to         derive the height of the tile rows with index greater than or         equal to num_exp_tile_rows_minus1 as specified in clause 6.5.1.         The value of tile_row_height_minus1[i] shall be in the range of         0 to PicHeightInCtbsY−1, inclusive. When not present, the value         of tile_row_height_minus1[0] is inferred to be equal to         PicHeightInCtbsY−1.         rect_slice_flag equal to 0 specifies that tiles within each         slice are in raster scan order and the slice information is not         signalled in PPS. rect_slice_flag equal to 1 specifies that         tiles within each slice cover a rectangular region of the         picture and the slice information is signalled in the PPS. When         not present, rect_slice_flag is inferred to be equal to 1. When         subpic_info_present_flag is equal to 1, the value of         rect_slice_flag shall be equal to 1.         single_slice_per_subpic_flag equal to 1 specifies that each         subpicture consists of one and only one rectangular slice.         single_slice_per_subpic_flag equal to 0 specifies that each         subpicture may consist of one or more rectangular slices. When         single_slice_per_subpic_flag is equal to 1,         num_slices_in_pic_minus1 is inferred to be equal to         sps_num_subpics_minus1. When not present, the value of         single_slice_per_subpic_flag is inferred to be equal to 0.         num_slices_in_pic_minus1 plus 1 specifies the number of         rectangular slices in each picture referring to the PPS. The         value of num_slices_in_pic_minus1 shall be in the range of 0 to         MaxSlicesPerPicture−1, inclusive, where MaxSlicesPerPicture is         specified in Annex A. When no_pic_partition_flag is equal to 1,         the value of num_slices_in_pic_minus1 is inferred to be equal to         0.         tile_idx_delta_present_flag equal to 0 specifies that         tile_idx_delta values are not present in the PPS and all         rectangular slices in pictures referring to the PPS are         specified in raster order according to the process defined in         clause 6.5.1. tile_idx_delta_present_flag equal to 1 specifies         that tile_idx_delta values may be present in the PPS and all         rectangular slices in pictures referring to the PPS are         specified in the order indicated by the values of         tile_idx_delta. When not present, the value of         tile_idx_delta_present_flag is inferred to be equal to 0.         slice_width_in_tiles_minus1[i] plus 1 specifies the width of the         i-th rectangular slice in units of tile columns. The value of         slice_width_in_tiles_minus1[i] shall be in the range of 0 to         NumTileColumns−1, inclusive. When slice_width_in_tiles_minus1[i]         is not present, the following applies:     -   If NumTileColumns is equal to 1, the value of         slice_width_in_tiles_minus1[i] is inferred to be equal to 0.     -   Otherwise, the value of slice_width_in_tiles_minus1[i] is         inferred as specified in clause 6.5.1.         slice_height_in_tiles_minus1[i] plus 1 specifies the height of         the i-th rectangular slice in units of tile rows. The value of         slice_height_in_tiles_minus1[i] shall be in the range of 0 to         NumTileRows−1, inclusive. When slice_height_in_tiles_minus1[i]         is not present, the following applies:     -   If NumTileRows is equal to 1, or tile_idx_delta_present_flag is         equal to 0 and tileIdx % NumTileColumns is greater than 0), the         value of slice_height_in_tiles_minus1[i] is inferred to be equal         to 0.     -   Otherwise (NumTileRows is not equal to 1, and         tile_idx_delta_present_flag is equal to 1 or tileIdx %         NumTileColumns is equal to 0), when tile_idx_delta_present_flag         is equal to 1 or tileIdx % NumTileColumns is equal to 0, the         value of slice_height_in_tiles_minus1[i] is inferred to be equal         to slice_height_in_tiles_minus1[i−1].         num_exp_slices_in_tile[i] specifies the number of explicitly         provided slice heights in the current tile that contains more         than one rectangular slices. The value of         num_exp_slices_in_tile[i] shall be in the range of 0 to         RowHeight[tileY]−1, inclusive, where tileY is the tile row index         containing the i-th slice. When not present, the value of         num_exp_slices_in_tile[i] is inferred to be equal to 0. When         num_exp_slices_in_tile[i] is equal to 0, the value of the         variable NumSlicesInTile[i] is derived to be equal to 1.         exp_slice_height_in_ctus_minus1[j] plus 1 specifies the height         of the j-th rectangular slice in the current tile in units of         CTU rows. The value of exp_slice_height_in_ctus_minus1[j] shall         be in the range of 0 to RowHeight[tileY]−1, inclusive, where         tileY is the tile row index of the current tile.         When num_exp_slices_in_tile[i] is greater than 0, the variable         NumSlicesInTile[i] and SliceHeightInCtusMinus1[i+k] fork in the         range of 0 to NumSlicesInTile[i]−1 are derived as follows:

remainingHeightInCtbsY = RowHeight[ SliceTopLeftTileIdx[ i ] / NumTileColumns ] numExpSliceInTile = num_exp_slices_in_tile[ i ] for( j = 0; j < numExpSliceInTile − 1; j++ ) {  SliceHeightInCtusMinus1[ i++ ] =  exp_slice_height_in_ctu_minus1[ j ]  remainingHeightInCtbsY −= SliceHeightInCtusMinus1[ j ] } uniformSliceHeightMinus1 = SliceHeightInCtusMinus1[ i − 1 ] (81) while( remainingHeightInCtbsY >= (uniformSliceHeightMinus1 + 1) ) {  SliceHeightInCtusMinus1[ i++ ] = uniformSliceHeightMinus1  remainingHeightInCtbsY −= (uniformSliceHeightMinus1 + 1)  j++ } if( remainingHeightInCtbsY > 0 ) {  SliceHeightInCtusMinus1[ i++ ] = remainingHeightInCtbsY  j++ } NumSlicesInTile[ i ] = j tile_idx_delta[i] specifies the difference between the tile index of the first tile in the i-th rectangular slice and the tile index of the first tile in the (i+1)-th rectangular slice. The value of tile_idx_delta[i] shall be in the range of −NumTilesInPic+1 to NumTilesInPic−1, inclusive. When not present, the value of tile_idx_delta[i] is inferred to be equal to 0. When present, the value of tile_idx_delta[i] shall not be equal to 0. loop_filter_across_tiles_enabled_flag equal to 1 specifies that in-loop filtering operations may be performed across tile boundaries in pictures referring to the PPS. loop_filter_across_tiles_enabled_flag equal to 0 specifies that in-loop filtering operations are not performed across tile boundaries in pictures referring to the PPS. The in-loop filtering operations include the deblocking filter, sample adaptive offset filter, and adaptive loop filter operations. When not present, the value of loop_filter_across_tiles_enabled_flag is inferred to be equal to 1. loop_filter_across_slices_enabled_flag equal to 1 specifies that in-loop filtering operations may be performed across slice boundaries in pictures referring to the PPS. loop_filter_across_slice_enabled_flag equal to 0 specifies that in-loop filtering operations are not performed across slice boundaries in pictures referring to the PPS. The in-loop filtering operations include the deblocking filter, sample adaptive offset filter, and adaptive loop filter operations. When not present, the value of loop_filter_across_slices_enabled_flag is inferred to be equal to 0. cabac_init_present_flag equal to 1 specifies that cabac_init_flag is present in slice headers referring to the PPS. cabac_init_present_flag equal to 0 specifies that cabac_init_flag is not present in slice headers referring to the PPS. num_ref_idx_default_active_minus1[i] plus 1, when i is equal to 0, specifies the inferred value of the variable NumRefIdxActive[0] for P or B slices with num_ref_idx_active_override_flag equal to 0, and, when i is equal to 1. specifies the inferred value of NumRefIdxActive[1] for B slices with num_ref_idx_active_override_flag equal to 0. The value of num_ref_idx_default_active_minus1[i] shall be in the range of 0 to 14, inclusive. rpl1_idx_present_flag equal to 0 specifies that ref_pic_list_sps_flag[1] and ref_pic_list_idx[1] are not present in the PH syntax structures or the slice headers for pictures referring to the PPS. rpl1_idx_present_flag equal to 1 specifies that ref_pic_list_sps_flag[1] and ref_pic_list_idx[1] may be present in the PH syntax structures or the slice headers for pictures referring to the PPS. init_qp_minus26 plus 26 specifies the initial value of SliceQp_(Y) for each slice referring to the PPS. The initial value of SliceQp_(Y) is modified at the picture level when a non-zero value of ph_qp_delta is decoded or at the slice level when a non-zero value of slice_qp_delta is decoded. The value of init_qp_minus26 shall be in the range of −(26+QpBdOffset) to +37, inclusive. cu_qp_delta_enabled_flag equal to 1 specifies that the ph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slice syntax elements are present in PHs referring to the PPS and cu_qp_delta_abs may be present in the transform unit syntax. cu_qp_delta_enabled_flag equal to 0 specifies that the ph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slice syntax elements are not present in PHs referring to the PPS and cu_qp_delta_abs is not present in the transform unit syntax. pps_chroma_tool_offsets_present_flag equal to 1 specifies that chroma tool offsets related syntax elements are present in the PPS RBSP syntax structure. pps_chroma_tool_offsets_present_flag equal to 0 specifies that chroma tool offsets related syntax elements are not present in in the PPS RBSP syntax structure. When ChromaArrayType is equal to 0, the value of pps_chroma_tool_offsets_present_flag shall be equal to 0. pps_cb_qp_offset and pps_cr_qp_offset specify the offsets to the luma quantization parameter Qp′_(Y) used for deriving Qp′_(Cb), and Qp′_(Cr), respectively. The values of pps_cb_qp_offset and pps_cr_qp_offset shall be in the range of −12 to +12, inclusive. When ChromaArrayType is equal to 0, pps_cb_qp_offset and pps_cr_qp_offset are not used in the decoding process and decoders shall ignore their value. When not present, the values of pps_cb_qp_offset and pps_cr_qp_offset are inferred to be equal to 0. pps_joint_cbcr_qp_offset_present_flag equal to 1 specifies that pps_joint_cbcr_qp_offset_value and joint_cbcr_qp_offset_list[i] are present in the PPS RBSP syntax structure. pps_joint_cbcr_qp_offset_present_flag equal to 0 specifies that pps_joint_cbcr_qp_offset_value and joint_cbcr_qp_offset_list[i] are not present in the PPS RBSP syntax structure. When ChromaArrayType is equal to 0 or sps_joint_cbcr_enabled_flag is equal to 0, the value of pps_joint_cbcr_qp_offset_present_flag shall be equal to 0. When not present, the value of pps_joint_cbcr_qp_offset_present_flag is inferred to be equal to 0. pps_joint_cbcr_qp_offset_value specifies the offset to the luma quantization parameter Qp′_(Y) used for deriving Qp′_(CbCr). The value of pps_joint_cbcr_qp_offset_value shall be in the range of −12 to +12, inclusive. When ChromaArrayType is equal to 0 or sps_joint_cbcr_enabled_flag is equal to 0. pps_joint_cbcr_qp_offset_value is not used in the decoding process and decoders shall ignore its value. When pps_joint_cbcr_qp_offset_present_flag is equal to 0, pps_joint_cbcr_qp_offset_value is not present and is inferred to be equal to 0. pps_slice_chroma_qp_offsets_present_flag equal to 1 specifies that the slice_cb_qp_offset and slice_cr_qp_offset syntax elements are present in the associated slice headers. pps_slice_chroma_qp_offsets_present_flag equal to 0 specifies that the slice_cb_qp_offset and slice_cr_qp_offset syntax elements are not present in the associated slice headers. When not present, the value of pps_slice_chroma_qp_offsets_present_flag is inferred to be equal to 0. pps_cu_chroma_qp_offset_list_enabled_flag equal to 1 specifies that the ph_cu_chroma_qp_offset_subdiv_intra_slice and ph_cu_chroma_qp_offset_subdiv_inter_slice syntax elements are present in PHs referring to the PPS and cu chroma_qp_offset_flag may be present in the transform unit syntax and the palette coding syntax. pps_cu_chroma_qp_offset_list_enabled_flag equal to 0 specifies that the ph_cu_chroma_qp_offset_subdiv_intra_slice and ph_cu_chroma_qp_offset_subdiv_inter_slice syntax elements are not present in PHs referring to the PPS and the cu_chroma_qp_offset_flag is not present in the transform unit syntax and the palette coding syntax. When not present, the value of pps_cu_chroma_qp_offset_list_enabled_flag is inferred to be equal to 0. chroma_qp_offset_list_len_minus1 plus 1 specifies the number of cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i]. syntax elements that are present in the PPS RBSP syntax structure. The value of chroma_qp_offset_list_len_minus1 shall be in the range of 0 to 5, inclusive. cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i], specify offsets used in the derivation of Qp′_(Cb), Qp′_(Cr), and Qp′_(CbCr), respectively. The values of cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i] shall be in the range of −12 to +12, inclusive. When pps_joint_cbcr_qp_offset_present_flag is equal to 0, joint_cbcr_qp_offset_list[i] is not present and it is inferred to be equal to 0. pps_weighted_pred_flag equal to 0 specifies that weighted prediction is not applied to P slices referring to the PPS. pps_weighted_pred_flag equal to 1 specifies that weighted prediction is applied to P slices referring to the PPS. When sps_weighted_pred_flag is equal to 0, the value of pps_weighted_pred_flag shall be equal to 0. pps_weighted_bipred_flag equal to 0 specifies that explicit weighted prediction is not applied to B slices referring to the PPS. pps_weighted_bipred_flag equal to 1 specifies that explicit weighted prediction is applied to B slices referring to the PPS. When sps_weighted_bipred_flag is equal to 0, the value of pps_weighted_bipred_flag shall be equal to 0. deblocking_filter_control_present_flag equal to 1 specifies the presence of deblocking filter control syntax elements in the PPS. deblocking_filter_control_present_flag equal to 0 specifies the absence of deblocking filter control syntax elements in the PPS. deblocking_filter_override_enabled_flag equal to 1 specifies the presence of ph_deblocking_filter_override_flag in the PHs referring to the PPS or slice_deblocking_filter_override_flag in the slice headers referring to the PPS. deblocking_filter_override_enabled_flag equal to 0 specifies the absence of ph_deblocking_filter_override_flag in PHs referring to the PPS or slice_deblocking_filter_override_flag in slice headers referring to the PPS. When not present, the value of deblocking_filter_override_enabled_flag is inferred to be equal to 0. pps_deblocking_filter_disabled_flag equal to 1 specifies that the operation of deblocking filter is not applied for slices referring to the PPS in which slice_deblocking_filter_disabled_flag is not present. pps_deblocking_filter_disabled_flag equal to 0 specifies that the operation of the deblocking filter is applied for slices referring to the PPS in which slice_deblocking_filter_disabled_flag is not present. When not present, the value of pps_deblocking_filter_disabled_flag is inferred to be equal to 0. pps_beta_offset_div2 and pps_tc_offseet_dv2 specify the default deblocking parameter offsets for β and tC (divided by 2) that are applied to the luma component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the picture headers or the slice headers of the slices referring to the PPS. The values of pps_beta_offset_div2 and pps_tc_offset_div2 shall both be in the range of −12 to 12, inclusive. When not present, the values of pps_beta_offset_div2 and pps_tc_offset_div2 are both inferred to be equal to 0. pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 specify the default deblocking parameter offsets for β and tC (divided by 2) that are applied to the Cb component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the picture headers or the slice headers of the slices referring to the PPS. The values of pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 shall both be in the range of −12 to 12, inclusive. When not present, the values of pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 are both inferred to be equal to 0. pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 specify the default deblocking parameter offsets for β and tC (divided by 2) that are applied to the Cr component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the picture headers or the slice headers of the slices referring to the PPS. The values of pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 shall both be in the range of −12 to 12, inclusive. When not present, the values of pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 are both inferred to be equal to 0. rpl_info_in_ph_flag equal to 1 specifies that reference picture list information is present in the PH syntax structure and not present in slice headers referring to the PPS that do not contain a PH syntax structure. rpl_info_in_ph_flag equal to 0 specifies that reference picture list information is not present in the PH syntax structure and may be present in slice headers referring to the PPS that do not contain a PH syntax structure. dbf_info_in_ph_flag equal to 1 specifies that deblocking filter information is present in the PH syntax structure and not present in slice headers referring to the PPS that do not contain a PH syntax structure. dbf_info_in_ph_flag equal to 0 specifies that deblocking filter information is not present in the PH syntax structure and may be present in slice headers referring to the PPS that do not contain a PH syntax structure. When not present, the value of dbf_info_in_ph_flag is inferred to be equal to 0. sao_info_in_ph_flag equal to 1 specifies that SAO filter information is present in the PH syntax structure and not present in slice headers referring to the PPS that do not contain a PH syntax structure. sao_info_in_ph_flag equal to 0 specifies that SAO filter information is not present in the PH syntax structure and may be present in slice headers referring to the PPS that do not contain a PH syntax structure. alf_info_in_ph_flag equal to 1 specifies that ALF information is present in the PH syntax structure and not present in slice headers referring to the PPS that do not contain a PH syntax structure. alf_info_in_ph_flag equal to 0 specifies that ALF information is not present in the PH syntax structure and may be present in slice headers referring to the PPS that do not contain a PH syntax structure. wp_info_in_ph_flag equal to 1 specifies that weighted prediction information may be present in the PH syntax structure and not present in slice headers referring to the PPS that do not contain a PH syntax structure. wp_info_in_ph_flag equal to 0 specifies that weighted prediction information is not present in the PH syntax structure and may be present in slice headers referring to the PPS that do not contain a PH syntax structure. When not present, the value of wp_info_in_ph_flag is inferred to be equal to 0. qp_delta_info_in_ph_flag equal to 1 specifies that QP delta information is present in the PH syntax structure and not present in slice headers referring to the PPS that do not contain a PH syntax structure. qp_delta_info_in_ph_flag equal to 0 specifies that QP delta information is not present in the PH syntax structure and may be present in slice headers referring to the PPS that do not contain a PH syntax structure. pps_ref_wraparound_enabled_flag equal to 1 specifies that horizontal wraparound nation compensation is applied in inter prediction. pps_ref_wraparound_enabled_flag equal to 0 specifies that horizontal wrap-around motion compensation is not applied. When the value of CtbSizeY/MinCbSizeY+1 is greater than pic_width_in_luma_samples/MinCbSizeY−1, the value of pps_ref_wraparound_enabled_flag shall be equal to 0. When sps_ref_wraparound_enabled_flag is equal to 0, the value of pps_ref_wraparound_enabled_flag shall be equal to 0. pps_ref_wraparound_offset plus (CtbSizeY/MinCbSizeY)+2 specifies the offset used for computing the horizontal wrap-around position in units of MinCbSizeY luma samples. The value of pps_ref_wraparound_offset shall be in the range of 0 to (pic_width_in_luma_samples/MinCbSizeY)−(CtbSizeY/MinCbSizeY)−2, inclusive. The variable PpsRefWraparoundOffset is set equal to pps_ref_wraparound_offset+(CtbSizeY/MinCbSizeY)+2. picture_header_extension_present_flag equal to 0 specifies that no PH extension syntax elements are present in PHs referring to the PPS. picture_header_extension_present_flag equal to 1 specifies that PH extension syntax elements are present in PHs referring to the PPS. picture_header_extension_present_flag shall be equal to 0 in bitstreams conforming to this version of this Specification. slice_header_extension_present_flag equal to 0 specifies that no slice header extension syntax elements are present in the slice headers for coded pictures referring to the PPS. slice_header_extension_present_flag equal to 1 specifies that slice header extension syntax elements are present in the slice headers for coded pictures referring to the PPS. slice_header_extension_present_flag shall be equal to 0 in bitstreams conforming to this version of this Specification. pps_extension_flag equal to 0 specifies that no pps_extension_data_flag syntax elements are present in the PPS RBSP syntax structure. pps_extension_flag equal to 1 specifies that there are pps_extension_data_flag syntax elements present in the PPS RBSP syntax structure. pps_extension_data_flag may have any value. Its presence and value do not affect decoder conformance to profiles specified in this version of this Specification. Decoders conforming to this version of this Specification shall ignore all pps_extension_data_flag syntax elements.

3.7. APS Syntax and Semantics

In the latest WC draft text, the APS syntax and semantics are as follows:

Descriptor adaptation_parameter_set_rbsp( ) {  adaptation_parameter_set_id u(5)  aps_params_type u(3)  if( aps_params_type = = ALF_APS )   alf_data( )  else if( aps_params_type = = LMCS_APS )   lmcs_data( )  else if( aps_params_type = = SCALING_APS )   scaling_list_data( )  aps_extension_flag u(1)  if( aps_extension_flag )   while( more_rbsp_data( ) )    aps_extension_data_flag u(1)  rbsp_trailing_bits( ) } The APS RBSP contains a ALF syntax structure, i.e., alf_data( ).

Descriptor alf_data( ) {  alf_luma_filter_signal_flag u(1)  alf_chroma_filter_signal_flag u(1)  alf_cc_cb_filter_signal_flag u(1)  alf_cc_cr_filter_signal_flag u(1)  if( alf_luma_filter_signal_flag ) {   alf_luma_clip_flag u(1)   alf_luma_num_filters_signalled_minus1 ue(v)   if( alf_luma_num_filters_signalled_minus1 > 0 )    for( filtIdx = 0; filtIdx < NumAlfFilters;    filtIdx++ )     alf_luma_coeff_delta_idx[ filtIdx ] u(v)   for( sfIdx = 0; sfIdx <=   alf_luma_num_filters_signalled_minus1; sfIdx++ )    for( j = 0; j < 12; j++ ) {     alf_luma_coeff_abs[ sfIdx ][ j ] ue(v)     if( alf_luma_coeff_abs[ sfIdx ][ j ] )      alf_luma_coeff_sign[ sfIdx ][ j ] u(1)    }   if( alf_luma_clip_flag )    for( sfIdx = 0; sfIdx <=   alf_luma_num_filters_signalled_minus1; sfIdx++ )     for( j = 0; j < 12; j++ )      alf_luma_clip_idx[ sfIdx ][ j ] u(2)  }  if( alf_chroma_filter_signal_flag ) {   alf_chroma_clip_flag u(1)   alf_chroma_num_alt_filters_minus1 ue(v)   for( altIdx = 0; altIdx <=   alf_chroma_num_alt_filters_minus1; altIdx++ ) {    for( j = 0; j < 6; j++ ) {     alf_chroma_coeff_abs[ altIdx ][ j ] ue(v)     if( alf_chroma_coeff_abs[ altIdx ][ j ] > 0 )      alf_chroma_coeff_sign[ altIdx ][ j ] u(1)    }    if( alf_chroma_clip_flag )     for( j = 0; j < 6; j++ )      alf_chroma_clip_idx[ altIdx ][ j ] u(2)   }  }  if( alf_cc_cb_filter_signal_flag ) {   alf_cc_cb_filters_signalled_minus1 ue(v)   for( k = 0; k < alf_cc_cb_filters_signalled_minus1 +   1; k++ ) {    for( j = 0; j < 7; j++ ) {     alf_cc_cb_mapped_coeff_abs[ k ][ j ] u(3)     if( alf_cc_cb_mapped_coeff_abs[ k ][ j ] )      alf_cc_cb_coeff_sign[ k ][ j ] u(1)    }   }  }  if( alf_cc_cr_filter_signal_flag ) {   alf_cc_cr_filters_signalled_minus1 ue(v)   for( k = 0; k < alf_cc_cr_filters_signalled_minus1 +   1; k++ ) {    for( j = 0; j < 7; j++ ) {     alf_cc_cr_mapped_coeff_abs[ k ][ j ] u(3)     if( alf_cc_cr_mapped_coeff_abs[ k ][ j ] )      alf_cc_cr_coeff_sign[ k ][ j ] u(1)    }   }  } } The APS RBSP contains a LMCS syntax structure, i.e., lmcs_data( ).

Descriptor lmcs_data( ) {  lmcs_min_bin_idx ue(v)  lmcs_delta_max_bin_idx ue(v)  lmcs_delta_cw_prec_minus1 ue(v)  for( i = lmcs_min_bin_idx; i <= LmcsMaxBinIdx; i++ ) {   lmcs_delta_abs_cw[ i ] u(v)   if( lmcs_delta_abs_cw[ i ] > 0 )    lmcs_delta_sign_cw_flag[ i ] u(1)  }  lmcs_delta_abs_crs u(3)  if( lmcs_delta_abs_crs > 0 )   lmcs_delta_sign_crs_flag u(1) } The APS RBSP contains a scaling list data syntax structure, i.e., scaling_list_data( ).

Descriptor scaling_list_data( ) {  scaling_matrix_for_lfnst_disabled_flag u(1)  scaling_list_chroma_present_flag u(1)  for( id = 0; id < 28; id ++ )   matrixSize = (id < 2 ) ? 2 : ( ( id < 8 ) ? 4 : 8 )   if( scaling_list_chroma_present_flag | |   ( id % 3 = = 2 ) | | ( id = = 27 ) ) {    scaling_list_copy_mode_flag[ id ] u(1)    if( !scaling_list_copy_mode_flag[ id ] )     scaling_list_pred_mode_flag[ id ] u(1)    if( ( scaling_list_copy_mode_flag[ id ] | |    scaling_list_pred_mode_flag[ id ] ) &&      id != 0 && id != 2 && id != 8 )     scaling_list_pred_id_delta[ id ] ue(v)    if( !scaling_list_copy_mode_flag[ id ] ) {     nextCoef = 0     if( id > 13 ) {      scaling_list_dc_coef[ id − 14 ] se(v)      nextCoef += scaling_list_dc_coef[ id − 14 ]     }     for( i = 0; i < matrixSize * matrixSize; i++ ) {      x = DiagScanOrder[ 3 ][ 3 ][ i ][ 0 ]      y = DiagScanOrder[ 3 ][ 3 ][ i ][ 1 ]      if( !( id > 25 && x >= 4 && y >= 4 ) ) {       scaling_list_delta_coef[ id ][ i ] se(v)       nextCoef += scaling_list_delta_coef[ id ][ i ]      }      ScalingList[ id ][ i ] = nextCoef     }    }   }  } } Each APS RBSP shall be available to the decoding process prior to it being referenced. included in at least one AU with TemporalId less than or equal to the TemporalId of the coded slice NAL unit that refers it or provided through external means. All APS NAL units with a particular value of adaptation_parameter_set_id and a particular value of aps_params_type within a PU, regardless of whether they are prefix or suffix APS NAL units, shall have the same content. adaptation_parameter_set_id provides an identifier for the APS for reference by other syntax elements. When aps_params_type is equal to ALF_APS or SCALING_APS, the value of adaptation_parameter_set_id shall be in the range of 0 to 7, inclusive. When aps_params_type is equal to LMCS_APS, the value of adaptation_parameter_set_id shall be in the range of 0 to 3, inclusive. Let apsLayerId be the value of the nuh_layer_id of a particular APS NAL unit, and vclLayerId be the value of the nuh_layer_id of a particular VCL NAL unit. The particular VCL NAL unit shall not refer to the particular APS NAL unit unless apsLayerId is less than or equal to vclLayerId and the layer with nuh_layer_id equal to apsLayerId is included in at least one OLS that includes the layer with nuh_layer_id equal to vclLayerId. aps_params_type specifies the type of APS parameters carried in the APS as specified in Table 6.

TABLE 6 APS parameters type codes and types of APS parameters Name of aps_params_type aps_params_type Type of APS parameters 0 ALF_APS ALF parameters 1 LMCS_APS LMCS parameters 2 SCALING_APS Scaling list parameters 3 . . . 7 Reserved Reserved All APS NAL units with a particular value of aps_params_type, regardless of the nuh_layer_id values. share the same value space for adaptation_parameter_set_id. APS NAL units with different values of aps_params_type use separate values spaces for adaptation_parameter_set_id.

-   -   NOTE 1—An APS NAL unit (with a particular value of         adaptation_parameter_set_id and a particular value of         aps_params_type) can be shared across pictures, and different         slices within a picture can refer to different ALF APSs.     -   NOTE 2—A suffix APS NAL unit associated with a particular VCL         NAL unit (this VCL NAL unit precedes the suffix APS NAL unit in         decoding order) is not for use by the particular VCL NAL unit,         but for use by VCL NAL units following the suffix APS NAL unit         in decoding order.         aps_extension_flag equal to 0 specifies that no         aps_extension_data_flag syntax elements are present in the APS         RBSP syntax structure. aps_extension_flag equal to 1 specifies         that there are aps_extension_data_flag syntax elements present         in the APS RBSP syntax structure.         aps_extension_data_flag may have any value. Its presence and         value do not affect decoder conformance to profiles specified in         this version of this Specification. Decoders conforming to this         version of this Specification shall ignore all         aps_extension_data_flag syntax elements.         alf_luma_filter_signal_flag equal to 1 specifies that a luma         filter set is signalled. alf_luma_filter_signal_flag equal to 0         specifies that a luma filter set is not signalled.         alf_chroma_filter_signal_flag equal to 1 specifies that a chroma         filter is signalled. alf_chroma_filter_signal_flag equal to 0         specifies that a chroma filter is not signalled. When         ChromaArrayType is equal to 0, alf_chroma_filter_signal_flag         shall be equal to 0.         At least one of the values of alf_luma_filter_signal_flag,         alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag and         alf_cc_cr_filter_signal_flag shall be equal to 1.         The variable NumAlfFilters specifying the number of different         adaptive loop filters is set equal to 25.         alf_luma_clip_flag equal to 0 specifies that linear adaptive         loop filtering is applied on luma component. alf_luma_clip_flag         equal to 1 specifies that non-linear adaptive loop filtering may         be applied on luma component.         alf_luma_num_filters_signalled_minus1 plus 1 specifies the         number of adaptive loop filter classes for which luma         coefficients can be signalled. The value of         alf_luma_num_filters_signalled_minus1 shall be in the range of 0         to NumAlfFilters−1, inclusive.         alf_luma_coeff_delta_idx[filtIdx] specifies the indices of the         signalled adaptive loop filter luma coefficient deltas for the         filter class indicated by filtIdx ranging from 0 to         NumAlfFilters−1. When alf_luma_coeff_delta_idx[filtIdx] is not         present, it is inferred to be equal to 0. The length of         alf_luma_coeff_delta_idx[filtIdx] is         Ceil(Log2(alf_luma_num_filters_signalled_minus1+1)) bits. The         value of alf_luma_coeff_delta_idx[filtIdx] shall be in the range         of 0 to alf_luma_num_filters_signalled_minus1, inclusive.         alf_luma_coeff_abs[sfIdx][j] specifies the absolute value of the         j-th coefficient of the signalled luma filter indicated by         sfIdx. When alf_luma_coeff_abs[sfIdx][j] is not present, it is         inferred to be equal 0. The value of         alf_luma_coeff_abs[sfIdx][j] shall be in the range of 0 to 128,         inclusive.         alf_luma_coeff_sign[sfIdx][j] specifies the sign of the j-th         luma coefficient of the filter indicated by sfIdx as follows:     -   If alf_luma_coeff_sign[sfIdx][j] is equal to 0, the         corresponding luma filter coefficient has a positive value.     -   Otherwise (alf_luma_coeff_sign[sfIdx][j] is equal to 1), the         corresponding luma filter coefficient has a negative value.         When alf_luma_coeff_sign[sfIdx][j] is not present, it is         inferred to be equal to 0.         The variable filtCoeff[sfIdx][j] with sfIdx=0 . . .         alf_luma_num_filters_signalled_minus1, j=0 . . . 11 is         initialized as follows:

filtCoeff[sfIdx][j]=alf_luma_coeff_abs[sfIdx][j]*(1−2*alf_luma_coeff_sign(sfIdx[1][j])  (93)

The luma filter coefficients AlfCoeff_(L)[adaptation_parameter_set_id] with elements AlfCoeff_(L)[adaptation_parameter_set_id][filtIdx][j], with filtIdx=0 . . . NumAlfFilters−1 and j=0 . . . 11 are derived as follows:

AlfCoeff_(L)[adaptation_parameter_set_id][filtIdx][j]=filtCoeff[alf_luma_coeff_delta_idx[filtIdx]][j]   (94)

The fixed filter coefficients AlfFixFiltCoeff[i][j] with i=0 . . . 64, j=0 . . . 11 and the class to filter mapping AlfClassToFiltMap[m][n] with m=0 . . . 15 and n=0 . . . 24 are derived as follows:

AlfFixFiltCoeff = (95)  {   { 0, 0, 2, −3, 1, −4, 1, 7, −1, 1, −1, 5}   { 0, 0, 0, 0, 0, −1, 0, 1, 0, 0, −1, 2}   { 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0}   { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, −1, 1}   { 2, 2, −7, −3, 0, −5, 13, 22, 12, −3, −3, 17}   {−1, 0, 6, −8, 1, −5, 1, 23, 0, 2, −5, 10}   { 0, 0, −1, −1, 0, −1, 2, 1, 0, 0, −1, 4}   { 0, 0, 3, −11, 1, 0, −1, 35, 5, 2, −9, 9}   { 0, 0, 8, −8, −2, −7, 4, 4, 2, 1, −1, 25}   { 0, 0, 1, −1, 0, −3, 1, 3, −1, 1, −1, 3}   { 0, 0, 3, −3, 0, −6, 5, −1, 2, 1, −4, 21}   {−7, 1, 5, 4, −3, 5, 11, 13, 12, −8, 11, 12}   {−5, −3, 6, −2, −3, 8, 14, 15, 2, −7, 11, 16}   { 2, −1, −6, −5, −2, −2, 20, 14, −4, 0, −3, 25}   { 3, 1, −8, −4, 0, −8, 22, 5, −3, 2, −10, 29}   { 2, 1, −7, −1, 2, −11, 23, −5, 0, 2, −10, 29}   {−6, −3, 8, 9, −4, 8, 9, 7, 14, −2, 8, 9}   { 2, 1, −4, −7, 0, −8, 17, 22, 1, −1, −4, 23}   { 3, 0, −5, −7, 0, −7, 15, 18, −5, 0, −5, 27}   { 2, 0, 0, −7, 1, −10, 13, 13, −4, 2, −7, 24}   { 3, 3, −13, 4, −2, −5, 9, 21, 25, −2, −3, 12}   {−5, −2, 7, −3, −7, 9, 8, 9, 16, −2, 15, 12}   { 0, −1, 0, −7, −5, 4, 11, 11, 8, −6, 12, 21}   { 3, −2, −3, −8, −4, −1, 16, 15, −2, −3, 3, 26}   { 2, 1, −5, −4, −1, −8, 16, 4, −2, 1, −7, 33}   { 2, 1, −4, −2, 1, −10, 17, −2, 0, 2, −11, 33}   { 1, −2, 7, −15, −16, 10, 8, 8, 20, 11, 14, 11}   { 2, 2, 3, −13, −13, 4, 8, 12, 2, −3, 16, 24}   { 1, 4, 0, −7, −8, −4, 9, 9, −2, −2, 8, 29}   { 1, 1, 2, −4, −1, −6, 6, 3, −1, −1, −3, 30}   {−7, 3, 2, 10, −2, 3, 7, 11, 19, −7, 8, 10}   { 0, −2, −5, −3, −2, 4, 20, 15, −1, −3, −1, 22}   { 3, −1, −8, −4, −1, −4, 22, 8, −4, 2, −8, 28}   { 0, 3, −14, 3, 0, 1, 19, 17, 8, −3, −7, 20}   { 0, 2, −1, −8, 3, −6, 5, 21, 1, 1, −9, 13}   {−4, −2, 8, 20, −2, 2, 3, 5, 21, 4, 6, 1}   { 2, −2, −3, −9, −4, 2, 14, 16, 3, −6, 8, 24}   { 2, 1, 5, −16, −7, 2, 3, 11, 15, −3, 11, 22}   { 1, 2, 3, −11, −2, −5, 4, 8, 9, −3, −2, 26}   { 0, −1, 10, −9, −1, −8, 2, 3, 4, 0, 0, 29}   { 1, 2, 0, −5, 1, −9, 9, 3, 0, 1, −7, 20}   {−2, 8, −6, −4, 3, −9, −8, 45, 14, 2, −13, 7}   { 1, −1, 16, −19, −8, −4, −3, 2, 19, 0, 4, 30}   { 1, 1, −3, 0, 2, −11, 15, −5, 1, 2, −9, 24}   { 0, 1, −2, 0, 1, −4, 4, 0, 0, 1, −4, 7}   { 0, 1, 2, −5, 1, −6, 4, 10, −2, 1, −4, 10}   { 3, 0, −3, −6, −2, −6, 14, 8, −1, −1, −3, 31}   { 0, 1, 0, −2, 1, −6, 5, 1, 0, 1, −5, 13}   { 3, 1, 9, −19, −21, 9, 7, 6, 13, 5, 15, 21}   { 2, 4, 3, −12, −13, 1, 7, 8, 3, 0, 12, 26}   { 3, 1, −8, −2, 0, −6, 18, 2, −2, 3, −10, 23}   { 1, 1, −4, −1, 1, −5, 8, 1, −1, 2, −5, 10}   { 0, 1, −1, 0, 0, −2, 2, 0, 0, 1, −2, 3}   { 1, 1, −2, −7, 1, −7, 14, 18, 0, 0, −7, 21}   { 0, 1, 0, −2, 0, −7, 8, 1, −2, 0, −3, 24}   { 0, 1, 1, −2, 2, −10, 10, 0, −2, 1, −7, 23}   { 0, 2, 2, −11, 2, −4, −3, 39, 7, 1, −10, 9}   { 1, 0, 13, −16, −5, −6, −1, 8, 6, 0, 6, 29}   { 1, 3, 1, −6, −4, −7, 9, 6, −3, −2, 3, 33}   { 4, 0, −17, −1, −1, 5, 26, 8, −2, 3, −15, 30}   { 0, 1, −2, 0, 2, −8, 12, −6, 1, 1, −6, 16}   { 0, 0, 0, −1, 1, −4, 4, 0, 0, 0, −3, 11}   { 0, 1, 2, −8, 2, −6, 5, 15, 0, 2, −7, 9}   { 1, −1, 12, −15, −7, −2, 3, 6, 6, −1, 7, 30}  }, AlfClassToFiltMap = (96)  {   { 8, 2, 2, 2, 3, 4, 53, 9, 9, 52, 4, 4, 5, 9, 2, 8, 10, 9, 1, 3, 39, 39, 10,  9, 52 }   { 11, 12, 13, 14, 15, 30, 11, 17, 18, 19, 16, 20, 20, 4, 53, 21, 22, 23,  14, 25, 26, 26, 27, 28, 10 }   { 16, 12, 31, 32, 14, 16, 30, 33, 53, 34, 35, 16, 20, 4, 7, 16, 21, 36,  18, 19, 21, 26, 37, 38, 39 }   { 35, 11, 13, 14, 43, 35, 16, 4, 34, 62, 35, 35, 30, 56, 7, 35, 21, 38,  24, 40, 16, 21, 48, 57, 39 }   { 11, 31, 32, 43, 44, 16, 4, 17, 34, 45, 30, 20, 20, 7, 5, 21, 22, 46,  40, 47, 26, 48, 63, 58, 10 }   { 12, 13, 50, 51, 52, 11, 17, 53, 45, 9, 30, 4, 53, 19, 0, 22, 23, 25,  43, 44, 37, 27, 28, 10, 55 }   { 30, 33, 62, 51, 44, 20, 41, 56, 34, 45, 20, 41, 41, 56, 5, 30, 56, 38,  40, 47, 11, 37, 42, 57, 8 }   { 35, 11, 23, 32, 14, 35, 20, 4, 17, 18, 21, 20, 20, 20, 4, 16, 21, 36,  46, 25, 41, 26, 48, 49, 58 }   { 12, 31, 59, 59, 3, 33, 33, 59, 59, 52, 4, 33, 17, 59, 55, 22, 36, 59,  259, 60, 22, 36, 59, 5, 55 }   { 31, 25, 15, 60, 60, 22, 17, 19, 55, 55, 20, 20, 53, 19, 55, 22, 46,  25, 43, 60, 37, 28, 10, 55, 52 }   { 12, 31, 32, 50, 51, 11, 33, 53, 19, 45, 16, 4, 4, 53, 5, 22, 36, 18,  25, 43, 26, 27, 27, 28, 10 }   { 5, 2, 44, 52, 3, 4, 53, 45, 9, 3, 4, 56, 5, 0, 2, 5, 10, 47, 52, 3, 63,  39, 10, 9, 52 }   { 12, 34, 44, 44, 3, 56, 56, 62, 45, 9, 56, 56, 7, 5, 0, 22, 38, 40, 47,  52, 48, 57, 39, 10, 9 }   { 35, 11, 23, 14, 51, 35, 20, 41, 56, 62, 16, 20, 41, 56, 7, 16, 21, 38,  24, 40, 26, 26, 42, 57, 39 }   { 33, 34, 51, 51, 52, 41, 41, 34, 62, 0, 41, 41, 56, 7, 5, 56, 38, 38,  40, 44, 37, 42, 57, 39, 10 }   { 16, 31, 32, 15, 60, 30, 4, 17, 19, 25, 22, 20, 4, 53, 19, 21, 22, 46,  25, 55, 26, 48, 63, 58, 55 }  }, It is a requirement of bitstream conformance that the values of AlfCoeff_(L)[adaptation_parameter_set_id][filtIdx][j] with filtIdx=0 . . . NumAlfFilters−1, j=0 . . . 11 shall be in the range of −2⁷ to 2⁷−1, inclusive. alf_luma_clip_id:[sfIdx][j] specifies the clipping index of the clipping value to use before multiplying by the j-th coefficient of the signalled luma filter indicated by sfIdx. It is a requirement of bitstream conformance that the values of alf_luma_clip_idx[sfIdx][j] with sfIdx=0 . . . alf_luma_num_filters_signalled_minus1 and j=0 . . . 11 shall be in the range of 0 to 3, inclusive. The luma filter clipping values AlfClip_(L)[adaptation_parameter_set_id] with elements AlfClip_(L)[adaptation_parameter_set_id][filtIdx][j], with filtIdx=0 . . . NumAlfFilters−1 and j=0 . . . 11 are derived as specified in Table 8 depending on BitDepth and clipIdx set equal to alf_luma_clip_idx[alf_luma_coeff_delta_idx[filtIdx]][j]. alf_chroma_clip_flag equal to 0 specifies that linear adaptive loop filtering is applied on chroma components; alf_chroma_clip_flag equal to 1 specifies that non-linear adaptive loop filtering is applied on chroma components. When not present, alf_chroma_clip_flag is inferred to be equal to 0. alf_chroma_num_alt_filters_minus1 plus 1 specifies the number of alternative filters for chroma components. The value of alf_chroma_num_alt_filters_minus1 shall be in the range of 0 to 7, inclusive. alf_chroma_coeff_abs[altIdx][j] specifies the absolute value of the j-th chroma filter coefficient for the alternative chroma filter with index altIdx. When alf_chroma_coeff_abs[altIdx][j] is not present, it is inferred to be equal 0. The value of alf_chroma_coeff_abs[sfIdx][j] shall be in the range of 0 to 128, inclusive. alf_chroma_coeff_sign[altIdx][j] specifies the sign of the j-th chroma filter coefficient for the alternative chroma filter with index altIdx as follows:

-   -   If alf_chroma_coeff_sign[altIdx][j] is equal to 0, the         corresponding chroma filter coefficient has a positive value.     -   Otherwise (alf_chroma_coeff_sign[altIdx][j] is equal to 1), the         corresponding chroma filter coefficient has a negative value.         When alf_chroma_coeff_sign[altIdx][j] is not present, it is         inferred to be equal to 0.         The chroma filter coefficients         AlfCoeff_(C)[adaptation_parameter_set_id][altIdx] with elements         AlfCoeff_(C)[adaptation_parameter_set_id][altIdx][j], with         altIdx=0 . . . alf_chroma_num_alt_filters_minus1, j=0 . . . 5         are derived as follows:

AlfCoeff_(C)[adaptation_parameter_set_id][altIdx][j]=alf_chroma_coeff_abs[altIdx][j]*(1−2*alf_chroma_coeff_sign[altIdx][j]  (97)

It is a requirement of bitstream conformance that the values of AlfCoeff_(C)[adaptation_parameter_set_id][altIdx][j] with altIdx=0 . . . alf_chroma_num_alt_filters_minus1, j=0 . . . 5 shall be in the range of −2⁷ to 2⁷−1, inclusive. alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-component filters for the Cb colour component are signalled. alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-component filters for Cb colour component are not signalled. When ChromaArrayType is equal to 0. alf_cc_cb_filter_signal_flag shall be equal to 0. alf_cc_cb_filters_signalled_minus1 plus 1 specifies the number of cross-component filters for the Cb colour component signalled in the current ALF APS. The value of alf_cc_cb_filters_signalled_minus1 shall be in the range of 0 to 3, inclusive. alf_cc_cb_mapped_coeff_abs[k][j] specifies the absolute value of the j-th mapped coefficient of the signalled k-th cross-component filter for the Cb colour component. When alf_cc_cb_mapped_coeff_abs[k][j] is not present, it is inferred to be equal to 0. alf_cc_cb_coeff_sign[k][j] specifies the sign of the j-th coefficient of the signalled k-th cross-component filter for the Cb colour component as follows:

-   -   If alf_cc_cb_coeff_sign[k][j] is equal to 0, the corresponding         cross-component filter coefficient has a positive value.     -   Otherwise (alf_cc_cb_sign[k][j] is equal to 1), the         corresponding cross-component filter coefficient has a negative         value.         When alf_cc_cb_coeff_sign[k][j] is not present, it is inferred         to be equal to 0.         The signalled k-th cross-component filter coefficients for the         Cb colour component         CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j], with j=0         . . . 6 are derived as follows:     -   If alf_cc_cb_mapped_coeff_abs[k][j] is equal to 0,         CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j] is set         equal to 0.     -   Otherwise, CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j]         is set equal to         (1−2*alf_cc_cb_coeff_sign[k][j])*2^(alf_cc_cb_mapped_coeff_abs[k][j]−1).         alf_cc_cr_filter_signal_flag equal to 1 specifies that         cross-component filters for the Cr colour component are         signalled. alf_cc_cr_filter_signal_flag equal to 0 specifies         that cross-component filters for the Cr colour component are not         signalled. When ChromaArrayType is equal to 0.         alf_cc_cr_filter_signal_flag shall be equal to 0.         alf_cc_cr_filters_signalled_minus1 plus 1 specifies the number         of cross-component filters for the Cr colour component signalled         in the current ALF APS. The value of         alf_cc_cr_filters_signalled_minus1 shall be in the range of 0 to         3, inclusive.         alf_cc_cr_mapped_coeff_abs[k][j] specifies the absolute value of         the j-th mapped coefficient of the signalled k-th         cross-component filter for the Cr colour component. When         alf_cc_cr_mapped_coeff_abs[k][j] is not present, it is inferred         to be equal to 0.         alf_cc_cr_coeff_sign[k][j] specifies the sign of the j-th         coefficient of the signalled k-th cross-component filter for the         Cr colour component as follows:     -   If alf_cc_cr_coeff_sign[k][j] is equal to 0, the corresponding         cross-component filter coefficient has a positive value.     -   Otherwise (alf_cc_cr_sign[k][j] is equal to 1), the         corresponding cross-component filter coefficient has a negative         value.         When alf_cc_cr_coeff_sign[k][j] is not present, it is inferred         to be equal to 0.         The signalled k-th cross-component filter coefficients for the         Cr colour component         CcAlfApsCoeff_(Cr)[adaptation_parameter_set_id][k][j], with j=0         . . . 6 are derived as follows:     -   If alf_cc_cr_mapped_coeff_abs[k][j] is equal to 0.         CcAlfApsCoeff_(Cr)[adaptation_parameter_set_id][k][j] is set         equal to 0.     -   Otherwise, CcAlfApsCoeff_(Cr)[adaptation_parameter_set_id][k][j]         is set equal to         (1−2*alf_cc_cr_coeff_sign[k][j])*2^(alf_cc_cr_mapped_coeff_abs[k][j]−1).         alf_chroma_clip_idx[altIdx][j] specifies the clipping index of         the clipping value to use before multiplying by the j-th         coefficient of the alternative chroma filter with index altIdx.         It is a requirement of bitstream conformance that the values of         alf_chroma_clip_idx[altIdx][j] with altIdx=0 . . .         alf_chroma_num_alt_filters_minus1, j=0 . . . 5 shall be in the         range of 0 to 3, inclusive.         The chroma filter clipping values         AlfClip_(C)[adaptation_parameter_set_id][altIdx] with elements         AlfClip_(C)[adaptation_parameter_set_id][altIdx][j], with         altIdx=0 . . . alf_chroma_num_alt_filters_minus1, j=0 . . . 5         are derived as specified in Table 8 depending on BitDepth and         clipIdx set equal to alf_chroma_clip_idx[altIdx][j].

TABLE 8 Specification AlfClip depending on BitDepth and clipIdx clipIdx BitDepth 0 1 2 3 8 2⁸  2⁵ 2³ 2¹ 9 2⁹  2⁶ 2⁴ 2² 10 2¹⁰ 2⁷ 2⁵ 2³ 11 2¹¹ 2⁸ 2⁶ 2⁴ 12 2¹² 2⁹ 2⁷ 2⁵ 13 2¹³  2¹⁰ 2⁸ 2⁶ 14 2¹⁴  2¹¹ 2⁹ 2⁷ 15 2¹⁵  2¹²  2¹⁰ 2⁸ 16 2¹⁶  2¹³  2¹¹ 2⁹ lmcs_min_bin_idx specifies the minimum bin index used in the luma mapping with chroma scaling construction process. The value of lmcs_min_bin_idx shall be in the range of 0 to 15, inclusive. lmcs_delta_max_bin_idx specifies the delta value between 15 and the maximum bin index LmcsMaxBinIdx used in the luma mapping with chroma scaling construction process. The value of lmcs_delta_max_bin_idx shall be in the range of 0 to 15, inclusive. The value of LmcsMaxBinIdx is set equal to 15−lmcs_delta_max_bin_idx. The value of LmcsMaxBinIdx shall be greater than or equal to lmcs_min_bin_idx. lmcs_delta_cw_prec_minus1 plus 1 specifies the number of bits used for the representation of the syntax lmcs_delta_abs_cw[i]. The value of lmcs_delta_cw_prec_minus1 shall be in the range of 0 to BitDepth−2, inclusive. lmcs_delta_abs_cw[i] specifies the absolute delta codeword value for the ith bin. lmcs_delta_sign_cw_flag[i] specifies the sign of the variable lmcsDeltaCW[i] as follows:

-   -   If lmcs_delta_sign_cw_flag[i] is equal to 0, lmcsDeltaCW[i] is a         positive value.     -   Otherwise (lmcs_delta_sign_cw_flag[i] is not equal to 0).         lmcsDeltaCW [i] is a negative value.         When lmcs_delta_sign_cw_flag[i] is not present, it is inferred         to be equal to 0.         The variable OrgCW is derived as follows:

OrgCW=(1<<BitDepth)/16  (98)

The variable lmcsDeltaCW[i], with i=lmcs_min_bin_idx . . . LmcsMaxBinIdx, is derived as follows:

lmcsDeltaCW[i]=(1−2*lmcs_delta_sign_cw_flag[i])*lmcs_delta_abs_cw[i]  (99)

The variable lmcsCW[1] is derived as follows:

-   -   For i=0 . . . lmcs_min_bin_idx−1, lmcsCW[i] is set equal 0.     -   For i=lmcs_min_bin_idx . . . LmcsMaxBinIdx, the following         applies:

lmcsCW[i]=OrgCW+lmcsDeltaCW[i]  (100)

The value of lmcsCW[i] shall be in the range of (OrgCW>>3) to (OrgCW<<3−1), inclusive

-   -   For i=LmcsMaxBinIdx+1 . . . 15, lmcsCW[i] is set equal 0.         It is a requirement of bitstream conformance that the following         condition is true:

Σ_(i=0) ¹⁵lmcsCW[i]<=(1<<BitDepth)−1  (101)

The variable InputPivot[i], with i=0 . . . 16, is derived as follows:

InputPivot[i]=i*OrgCW  (102)

The variable LmcsPivot[i] with i=0 . . . 16, the variables ScaleCoeff[i] and InvScaleCoeff[i] with i=0 . . . 15, are derived as follows:

LmcsPivot[ 0 ] = 0; for( i = 0; i <= 15; i++ ) {  LmcsPivot[ i + 1 ] = LmcsPivot[ i ] + lmcsCW[ i ]  ScaleCoeff[ i ] = ( lmcsCW[ i ] * (1 << 11) + ( 1 << ( Log2(  OrgCW ) − 1 ) ) ) >> ( Log2( OrgCW ) )  if( lmcsCW[ i ] = = 0 ) (103)   InvScaleCoeff[ i ] = 0  else   InvScaleCoeff[ i ] = OrgCW * ( 1 << 11 ) / lmcsCW[ i ] } It is a requirement of bitstream conformance that, for i=lmcs_min_bin_idx . . . LmcsMaxBinIdx, when the value of LmcsPivot[i] is not a multiple of 1<<(BitDepth−5), the value of (LmcsPivot[i]>>(BitDepth−5)) shall not be equal to the value of (LmcsPivot[i+1]>>(BitDepth−5)). lmcs_delta_abs_crs specifies the absolute codeword value of the variable lmcsDeltaCrs. The value of lmcs_delta_abs_crs shall be in the range of 0 and 7, inclusive. When not present, lmcs_delta_abs_crs is inferred to be equal to 0. lmcs_delta_sign_crs_flag specifies the sign of the variable lmcsDeltaCrs. When not present, lmcs_delta_sign_crs_flag is inferred to be equal to 0. The variable lmcsDeltaCrs is derived as follows:

lmcsDeltaCrs=(1−2*lmcs_delta_sign_crs_flag)*lmcs_delta_abs_crs  (104)

It is a requirement of bitstream conformance that, when lmcsCW[i] is not equal to 0, (lmcsCW[i]+lmcsDeltaCrs) shall be in the range of (OrgCW>>3) to ((OrgCW<<3)−1), inclusive. The variable ChromaScaleCoeff[i], with i=0 . . . 15, is derived as follows:

if( lmcsCW[ i ] = = 0 )  ChromaScaleCoeff[ i ] = ( 1 << 11 ) else  ChromaScaleCoeff[ i ] = OrgCW * ( 1 << 11 ) / ( lmcsCW[ i ] +  lmcsDeltaCrs ) scaling_matrix_for_lfnst_disabled_flag equal to 1 specifies that scaling matrices are not applied to blocks coded with LFNST. scaling_matrix_for_lfnst_disabled_flag equal to 0 specifies that the scaling matrices may apply to the blocks coded with LFNST. scaling_list_chroma_present_flag equal to 1 specifies that chroma scaling lists are present in scaling_list_data( ). scaling_list_chroma_present_flag equal to 0 specifies that chroma scaling lists are not present in scaling_list_data( ). It is a requirement of bitstream conformance that scaling_list_chroma_present_flag shall be equal to 0 when ChromaArrayType is equal to 0, and shall be equal to 1 when ChromaArrayType is not equal to 0. scaling_list_copy_mode_flag[id] equal to 1 specifies that the values of the scaling list are the same as the values of a reference scaling list. The reference scaling list is specified by scaling_list_pred_id_delta[id]. scaling_list_copy_mode_flag[id] equal to 0 specifies that scaling_list_pred_mode_flag is present. scaling_list_pred_mode_flag[id] equal to 1 specifies that the values of the scaling list can be predicted from a reference scaling list. The reference scaling list is specified by scaling_list_pred_id_delta[id]. scaling_list_pred_mode_flag[id] equal to 0 specifies that the values of the scaling list are explicitly signalled. When not present, the value of scaling_list_pred_mode_flag[id] is inferred to be equal to 0. scaling_list_pred_id_delta[id] specifies the reference scaling list used to derive the predicted scaling matrix ScalingMatrixPred[id]. When not present, the value of scaling_list_pred_id_delta[id] is inferred to be equal to 0. The value of scaling_list_pred_id_delta[id] shall be in the range of 0 to maxIdDelta with maxIdDelta derived depending on id as follows:

maxIdDelta=(id<2)?id:((id<8)?(id−2):(id−8))  (106)

The variables refId and matrixSize are derived as follows:

refId=id−scaling_list_pred_id_delta[id]  (107)

matrixSize=(id<2)?2:((id<8)?4:8)  (108)

The (matrixSize)×(matrixSize) array ScalingMatrixPred[x][y] with x=0 . . . matrixSize−1, y=0 . . . matrixSize−1 and the variable ScalingMatrixDCPred are derived as follows:

-   -   When both scaling_list_copy_mode_flag[id] and         scaling_list_pred_mode_flag[id] are equal to 0, all elements of         ScalingMatrixPred are set equal to 8, and the value of         ScalingMatrixDCPred is set equal to 8.     -   Otherwise, when scaling_list_pred_id_delta[id] is equal to 0,         all elements of ScalingMatrixPred are set equal to 16, and         ScalingMatrixDCPred is set equal to 16.     -   Otherwise (either scaling_list_copy_mode_flag[id] or         scaling_list_pred_mode_flag[id] is equal to 1 and         scaling_list_pred_id_delta[id] is greater than 0),         ScalingMatrixPred is set equal to ScalingMatrixRec[refId], and         the following applies for ScalingMatrixDCPred:         -   If refId is greater than 13. ScalingMatrixDCPred is set             equal to ScalingMatrixDCRec[refId−14].         -   Otherwise (refId is less than or equal to 13),             ScalingMatrixDCPred is set equal to ScalingMatrixPred[0][0].             scaling_list_dc_coef[id−14] is used to derive the value of             the variable ScalingMatrixDC[id−14] when id is greater than             13 as follows:

ScalingMatrixDCRec[id−14](ScalingMatrixDCPred+scaling_list_dc_coef[id−14])&255  (109)

When not present, the value of scaling_list_dc_coef[id−14] is inferred to be equal to 0. The value of scaling_list_dc_coef[id−14] shall be in the range of −128 to 127, inclusive. The value of ScalingMatrixDCRec[id−14] shall be greater than 0. scaling_list_delta_coef[id][i] specifies the difference between the current matrix coefficient ScalingList[id][i] and the previous matrix coefficient ScalingList[id][i−1], when scaling_list_copy_mode_flag[id] is equal to 0. The value of scaling_list_delta_coef[id][i] shall be in the range of −128 to 127, inclusive. When scaling_list_copy_mode_flag[id] is equal to 1, all elements of ScalingList[id] are set equal to 0. The (matrixSize)×(matrixSize) array ScalingMatrixRec[id] is derived as follows:

ScalingMatrixRec[id][x][y]=(ScalingMatrixPred[x][y]+ScalingList[id][k])&255 with k=0 . . . (matrixSize*matrixSize−1),  (110)

-   -   x=DiagScanOrder[Log2(matrixSize)][Log2(matrixSize)][k][0], and     -   y=DiagScanOrder[Log2(matrixSize)][Log2(matrixSize)][k][1]         The value of ScalingMatrixRec[id][x][y] shall be greater than 0.

3.8. PH Syntax and Semantics

In the latest WC draft text, the PH syntax and semantics are as follows:

Descriptor picture_header_rbsp( ) {  picture_header_structure( )  rbsp_trailing_bits( ) } The PH RBSP contains a PH syntax structure, i.e., picture_header_structure( ).

Descriptor picture_header_structure( ) {  gdr_or_irap_pic_flag u(1)  if( gdr_or_irap_pic_flag )   gdr_pic_flag u(1)  ph_inter_slice_allowed_flag u(1)  if( ph_inter_slice_allowed_flag )   ph_intra_slice_allowed_flag u(1)  non_reference_picture_flag u(1)  ph_pic_parameter_set_id ue(v)  ph_pic_order_cnt_lsb u(v)  if( gdr_or_irap_pic_flag )   no_output_of_prior_pics_flag u(1)  if( gdr_pic_flag )   recovery_poc_cnt ue(v)  for( i = 0; i < NumExtraPhBits; i++ )   ph_extra_bit[ i ] u(1)  if( sps_poc_msb_flag ) {   ph_poc_msb_present_flag u(1)   if( ph_poc_msb_present_flag )    poc_msb_val u(v)  }  if( sps_alf_enabled_flag && alf_info_in_ph_flag ) {   ph_alf_enabled_flag u(1)   if( ph_alf_enabled_flag ) {    ph_num_alf_aps_ids_luma u(3)    for( i = 0; i < ph_num_alf_aps_ids_luma; i++ )     ph_alf_aps_id_luma[ i ] u(3)    if( ChromaArrayType != 0 )     ph_alf_chroma_idc u(2)    if( ph_alf_chroma_idc > 0 )     ph_alf_aps_id_chroma u(3)    if( sps_ccalf_enabled_flag ) {     ph_cc_alf_cb_enabled_flag u(1)     if( ph_cc_alf_cb_enabled_flag )      ph_cc_alf_cb_aps_id u(3)     ph_cc_alf_cr_enabled_flag u(1)     if( ph_cc_alf_cr_enabled_flag )      ph_cc_alf_cr_aps_id u(3)    }   }  }  if( sps_lmcs_enabled_flag ) {   ph_lmcs_enabled_flag u(1)   if( ph_lmcs_enabled_flag ) {    ph_lmcs_aps_id u(2)    if( ChromaArrayType != 0 )     ph_chroma_residual_scale_flag u(1)   }  }  if( sps_scaling_list_enabled_flag ) {   ph_scaling_list_present_flag u(1)   if( ph_scaling_list_present_flag )    ph_scaling_list_aps_id u(3)  }  if( sps_virtual_boundaries_enabled_flag && !sps_virtual_boundaries_present_flag ) {   ph_virtual_boundaries_present_flag u(1)   if( ph_virtual_boundaries_present_flag ) {    ph_num_ver_virtual_boundaries u(2)    for( i = 0; i < ph_num_ver_virtual_boundaries; i++ )     ph_virtual_boundaries_pos_x[ i ] u(13)    ph_num_hor_virtual_boundaries u(2)    for( i = 0; i < ph_num_hor_virtual_boundaries; i++ )     ph_virtual_boundaries_pos_y[ i ] u(13)   }  }  if( output_flag_present_flag )   pic_output_flag u(1)  if( rpl_info_in_ph_flag )   ref_pic_lists( )  if( partition_constraints_override_enabled_flag )   partition_constraints_override_flag u(1)  if( ph_intra_slice_allowed_flag ) {   if( partition_constraints_override_flag ) {    ph_log2_diff_min_qt_min_cb_intra_slice_luma ue(v)    ph_max_mtt_hierarchy_depth_intra_slice_luma ue(v)    if( ph_max_mtt_hierarchy_depth_intra_slice_luma != 0 ) {     ph_log2_diff_max_bt_min_qt_intra_slice_luma ue(v)     ph_log2_diff_max_tt_min_qt_intra_slice_luma ue(v)    }    if( qtbtt_dual_tree_intra_flag ) {     ph_log2_diff_min_qt_min_cb_intra_slice_chroma ue(v)     ph_max_mtt_hierarchy_depth_intra_slice_chroma ue(v)     if( ph_max_mtt_hierarchy_depth_intra_slice_chroma != 0 ) {      ph_log2_diff_max_bt_min_qt_intra_slice_chroma ue(v)      ph_log2_diff_max_tt_min_qt_intra_slice_chroma ue(v)     }    }   }   if( cu_qp_delta_enabled_flag )    ph_cu_qp_delta_subdiv_intra_slice ue(v)   if( pps_cu_chroma_qp_offset_list_enabled_flag )    ph_cu_chroma_qp_offset_subdiv_intra_slice ue(v)  }  if( ph_inter_slice_allowed_flag ) {   if( partition_constraints_override_flag ) {    ph_log2_diff_min_qt_min_cb_inter_slice ue(v)    ph_max_mtt_hierarchy_depth_inter_slice ue(v)    if( ph_max_mtt_hierarchy_depth_inter_slice != 0 ) {     ph_log2_diff_max_bt_min_qt_inter_slice ue(v)     ph_log2_diff_max_tt_min_qt_inter_slice ue(v)    }   }   if( cu_qp_delta_enabled_flag )    ph_cu_qp_delta_subdiv_inter_slice ue(v)   if( pps_cu_chroma_qp_offset_list_enabled_flag )    ph_cu_chroma_qp_offset_subdiv_inter_slice ue(v)   if( sps_temporal_mvp_enabled_flag ) {    ph_temporal_mvp_enabled_flag u(1)    if( ph_temporal_mvp_enabled_flag && rpl_info_in_ph_flag ) {     ph_collocated_from_l0_flag u(1)     if( ( ph_collocated_from_l0_flag &&       num_ref_entries[ 0 ][ RplsIdx[ 0 ] ] > 1 ) | |       ( !ph_collocated_from_l0_flag &&       num_ref_entries[ 1 ][ RplsIdx[ 1 ] ] > 1 ) )      ph_collocated_ref_idx ue(v)    }   }   mvd_l1_zero_flag u(1)   if( sps_fpel_mmvd_enabled_flag )    ph_fpel_mmvd_enabled_flag u(1)   if( sps_bdof_pic_present_flag )    ph_disable_bdof_flag u(1)   if( sps_dmvr_pic_present_flag )    ph_disable_dmvr_flag u(1)   if( sps_prof_pic_present_flag )    ph_disable_prof_flag u(1)   if( ( pps_weighted_pred_flag | | pps_weighted_bipred_flag ) && wp_info_in_ph_flag )    pred_weight_table( )  }  if( qp_delta_info_in_ph_flag )   ph_qp_delta se(v)  if( sps_joint_cbcr_enabled_flag )   ph_joint_cbcr_sign_flag u(1)  if( sps_sao_enabled_flag && sao_info_in_ph_flag ) {   ph_sao_luma_enabled_flag u(1)   if( ChromaArrayType != 0 )    ph_sao_chroma_enabled_flag u(1)  }  if( sps_dep_quant_enabled_flag )   ph_dep_quant_enabled_flag u(1)  if( sps_sign_data_hiding_enabled_flag && !ph_dep_quant_enabled_flag )   pic_sign_data_hiding_enabled_flag u(1)  if( deblocking_filter_override_enabled_flag && dbf_info_in_ph_flag ) {   ph_deblocking_filter_override_flag u(1)   if( ph_deblocking_filter_override_flag ) {    ph_deblocking_filter_disabled_flag u(1)    if( !ph_deblocking_filter_disabled_flag) {     ph_beta_offset_div2 se(v)     ph_tc_offset_div2 se(v)     ph_cb_beta_offset_div2 se(v)     ph_cb_tc_offset_div2 se(v)     ph_cr_beta_offset_div2 se(v)     ph_cr_tc_offset_div2 se(v)    }   }  }  if( picture_header_extension_present_flag ) {   ph_extension_length ue(v)   for( i = 0; i < ph_extension_length; i++)    ph_extension_data_byte[ i ] u(8)  } } The PH syntax structure contains information that is common for all slices of the coded picture associated with the PH syntax structure. gdr_or_irap_pic_flag equal to 1 specifies that the current picture is a GDR or IRAP picture. gdr_or_irap_pic_flag equal to 0 specifies that the current picture may or may not be a GDR or IRAP picture. gdr_pic_flag equal to 1 specifies the picture associated with the PH is a GDR picture. gdr_pic_flag equal to 0 specifies that the picture associated with the PH is not a GDR picture. When not present, the value of gdr_pic_flag is inferred to be equal to 0. When gdr_enabled_flag is equal to 0, the value of gdr_pic_flag shall be equal to 0. ph_inter_slice_allowed_flag equal to 0 specifies that all coded slices of the picture have slice_type equal to 2. ph_inter_slice_allowed_flag equal to 1 specifies that there may or may not be one or more coded slices in the picture that have slice_type equal to 0 or 1. ph_intra_slice_allowed_flag equal to 0 specifies that all coded slices of the picture have slice_type equal to 0 or 1. ph_intra_slice_allowed_flag equal to 1 specifies that there may or may not be one or more coded slices in the picture that have slice_type equal to 2. When not present, the value of ph_intra_slice_allowed_flag is inferred to be equal to 1.

-   -   NOTE 1—For bitstreams that are supposed to work subpicture based         bitstream merging without the need of changing PH NAL units, the         encoder is expected to set the values of both         ph_inter_slice_allowed_flag and ph_intra_slice_allowed_flag         equal to 1.         non_reference_picture_flag equal to 1 specifies the picture         associated with the PH is never used as a reference picture.         non_reference_picture_flag equal to 0 specifies the picture         associated with the PH may or may not be used as a reference         picture.         ph_pic_parameter_set_id specifies the value of         pps_pic_parameter_set_id for the PPS in use. The value of         ph_pic_parameter_set_id shall be in the range of 0 to 63,         inclusive.         It is a requirement of bitstream conformance that the value of         TemporalId of the PH shall be greater than or equal to the value         of TemporalId of the PPS that has pps_pic_narameter_set_id equal         to ph_pic_parameter_set_id.         ph_pic_order_cnt_lsb specifies the picture order count modulo         MaxPicOrderCntLsb for the current picture. The length of the         ph_pic_otder_cnt_lsb syntax element is         log2_max_pic_order_cnt_lsb_minus4+4 bits. The value of the         ph_pic_order_cnt_lsb shall be in the range of 0 to         MaxPicOrderCntLsb−1, inclusive.         no_output_of_prior_pics_flag affects the output of         previously-decoded pictures in the DPB after the decoding of a         CLVSS picture that is not the first picture in the bitstream as         specified in Annex C.         recovery_poc_cnt specifies the recovery point of decoded         pictures in output order. If the current picture is a GDR         picture that is associated with the PH, and there is a picture         picA that follows the current GDR picture in decoding order in         the CLVS that has PicOrdetCntVal equal to the PicOrderCntVal of         the current GDR picture plus the value of recovery_poc_cnt, the         picture picA is referred to as the recovery point picture.         Otherwise, the first picture in output order that has         PicOrderCntVal greater than the PicOrderCntVal of the current         picture plus the value of recovery_poc_cnt is referred to as the         recovery point picture. The recovery point picture shall not         precede the current GDR picture in decoding order. The value of         recovery_poc_cnt shall be in the range of 0 to         MaxPicOrderCntLsb−1, inclusive.         When the current picture is a GDR picture, the variable         RpPicOrderCntVal is derived as follows:

RpPicOrderCntVal=PicOrderCntVal+recovery_poc_cnt  (82)

-   -   NOTE 2—When gdr_enabled_flag is equal to 1 and PicOrderCntVal of         the current picture is greater than or equal to RpPicOrderCntVal         of the associated GDR picture, the current and subsequent         decoded pictures in output order are exact match to the         corresponding pictures produced by starting the decoding process         from the previous TRAP picture, when present preceding the         associated GDR picture in decoding order.         ph_extra_bit[i] may be equal to 1 or 0. Decoders conforming to         this version of this Specification shall ignore the value of         ph_extra_bit[i]. Its value does not affect decoder conformance         to profiles specified in this version of specification.         ph_poc_msb_present_flag equal to 1 specifies that the syntax         element poc_msb_val is present in the PH.         ph_poc_msb_present_flag equal to 0 specifies that the syntax         element poc_msb_val is not present in the PH. When         vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is         equal to 0 and there is a picture in the current AU in a         reference layer of the current layer, the value of         ph_poc_msb_present_flag shall be equal to 0.         poc_msb_val specifies the POC MSB value of the current picture.         The length of the syntax element poc_msb_val is         poc_msb_len_minus1+1 bits.         ph_alf_enabled_flag equal to 1 specifies that adaptive loop         filter is enabled for all slices associated with the PH and may         be applied to Y, Cb, or Cr colour component in the slices.         ph_alf_enabled_flag equal to 0 specifies that adaptive loop         filter may be disabled for one, or more, or all slices         associated with the PH. When not present, ph_alf_enabled_flag is         inferred to be equal to 0.         ph_num_alf_aps_ids_luma specifies the number of ALF APSs that         the slices associated with the PH refers to.         ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id         of the i-th ALF APS that the luma component of the slices         associated with the PH refers to.         The value of alf_luma_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i] shall         be equal to 1.         The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         ph_alf_aps_id_luma[i] shall be less than or equal to the         TemporalId of the picture associated with the PH.         ph_alf_chroma_idc equal to 0 specifies that the adaptive loop         filter is not applied to Cb and Cr colour components.         ph_alf_chroma_idc equal to 1 indicates that the adaptive loop         filter is applied to the Cb colour component. ph_alf_chroma_idc         equal to 2 indicates that the adaptive loop filter is applied to         the Cr colour component. ph_alf_chroma_idc equal to 3 indicates         that the adaptive loop filter is applied to Cb and Cr colour         components. When ph_alf_chroma_idc is not present, it is         inferred to be equal to 0.         ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id         of the ALF APS that the chroma component of the slices         associated with the PH refers to.         The value of alf_chroma_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to ph_alf_aps_id_chroma shall         be equal to 1.         The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         ph_alf_aps_id_chroma shall be less than or equal to the         TemporalId of the picture associated with the PH.         ph_cc_alf_cb_enabled_flag equal to 1 specifies that         cross-component filter for Cb colour component is enabled for         all slices associated with the PH and may be applied to Cb         colour component in the slices. ph_cc_alf_cb_enabled_flag equal         to 0 specifies that cross-component filter for Cb colour         component may be disabled for one, or more, or all slices         associated with the PH. When not present,         ph_cc_alf_cb_enabled_flag is inferred to be equal to 0.         ph_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id of         the ALF APS that the Cb colour component of the slices         associated with the PH refers to.         The value of alf_cc_cb_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_id shall         be equal to 1.         The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         ph_cc_alf_cb_aps_id shall be less than or equal to the         TemporalId of the picture associated with the PH.         ph_cc_alf_cr_enabled_flag equal to 1 specifies that         cross-component filter for Cr colour component is enabled for         all slices associated with the PH and may be applied to Cr         colour component in the slices. ph_cc_alf_cr_enabled_flag equal         to 0 specifies that cross-component filter for Cr colour         component may be disabled for one, or more, or all slices         associated with the PH. When not present,         ph_cc_alf_cr_enabled_flag is inferred to be equal to 0.         ph_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id of         the ALF APS that the Cr colour component of the slices         associated with the PH refers to.         The value of alf_cc_cr_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to ph_cc_alf_cr_aps_id shall         be equal to 1.         The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         ph_cc_alf_cr_aps_id shall be less than or equal to the         TemporalId of the picture associated with the PH.         ph_lmcs_enabled_flag equal to 1 specifies that luma mapping with         chroma scaling is enabled for all slices associated with the PH.         ph_lmcs_enabled_flag equal to 0 specifies that luma mapping with         chroma scaling may be disabled for one, or more, or all slices         associated with the PH. When not present, the value of         ph_lmcs_enabled_flag is inferred to be equal to 0.         ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the         LMCS APS that the slices associated with the PH refers to. The         TemporalId of the APS NAL unit having aps_params_type equal to         LMCS_APS and adaptation_parameter_set_id equal to ph_lmcs_aps_id         shall be less than or equal to the TemporalId of the picture         associated with PH.         ph_chroma_residual_scale_flag equal to 1 specifies that chroma         residual scaling is enabled for the all slices associated with         the PH. ph_chroma_residual_scale_flag equal to 0 specifies that         chroma residual scaling may be disabled for one, or more, or all         slices associated with the PH. When         ph_chroma_residual_scale_flag is not present, it is inferred to         be equal to 0.         ph_scaling_list_present_flag equal to 1 specifies that the         scaling list data used for the slices associated with the PH is         derived based on the scaling list data contained in the         referenced scaling list APS. ph_scaling_list_present_flag equal         to 0 specifies that the scaling list data used for the slices         associated with the PH is set to be equal to 16. When not         present, the value of ph_scaling_list_present_flag is inferred         to be equal to 0.         ph_scaling_list_aps_id specifies the adaptation_parameter_set_id         of the scaling list APS. The TemporalId of the APS NAL unit         having aps_params_type equal to SCALING_APS and         adaptation_parameter_set_id equal to ph_scaling_list_aps_id         shall be less than or equal to the TemporalId of the picture         associated with PH.         ph_virtual_boundaries_present_flag equal to 1 specifies that         information of virtual boundaries is signalled in the PH.         ph_virtual_boundaries_present_flag equal to 0 specifies that         information of virtual boundaries is not signalled in the PH.         When there is one or more than one virtual boundaries signalled         in the PH, the in-loop filtering operations are disabled across         the virtual boundaries in the picture. The in-loop filtering         operations include the deblocking filter, sample adaptive offset         filter, and adaptive loop filter operations. When not present,         the value of ph_virtual_boundaries_present_flag is inferred to         be equal to 0.         It is a requirement of bitstream conformance that, when         subpic_info_present_flag is equal to 1, the value of         ph_virtual_boundaries_present_flag shall be equal to 0.         The variable VirtualBoundariesPresentFlag is derived as follows:

VirtualBoundariesPresentFlag = 0 if( sps_virtual_boundaries_enabled_flag )  VirtualBoundariesPresentFlag = sps_virtual_boundaries_present_flag   | | ph_virtual_boundaries_present_flag (83) ph_num_ver_virtual_boundaries specifies the number of ph_virtual_boundaries_pos_x[i] syntax elements that are present in the PH. When ph_num_ver_virtual_boundaries is not present, it is inferred to be equal to 0. The variable NumVerVirtualBoundaries is derived as follows:

NumVerVirtualBoundaries = 0 if( sps_virtual_boundaries_enabled_flag )  NumVerVirtualBoundaries = sps_virtual_boundaries_present_flag ?   sps_num_ver_virtual_boundaries : (84)   ph_num_ver_virtual_boundaries ph_virtual_boundaries_pos_x[i] specifies the location of the i-th vertical virtual boundary in units of luma samples divided by 8. The value of ph_virtual_boundaries_pos_x[i] shall be in the range of 1 to Ceil(pic_width_in_luma_samples+8)−1, inclusive. The list VirtualBoundariesPosX[i] for i ranging from 0 to NumVerVirtualBoundaries−1, inclusive, in units of luma samples, specifying the locations of the vertical virtual boundaries, is derived as follows:

for( i = 0; i < NumVerVirtualBoundaries; i++)  VirtualBoundariesPosX[ i ] = ( sps_virtual_boundaries_present_flag ?  sps_virtual_boundaries_pos_x[ i ] : (85)  ph_virtual_boundaries_pos_x[ i ] ) * 8 The distance between any two vertical virtual boundaries shall be greater than or equal to CtbSizeY luma samples. ph_num_hor_virtual_boundaries specifies the number of ph_virtual_boundaries_pos_y[i] syntax elements that are present in the PH. When ph_num_hor_virtual_boundaries is not present, it is inferred to be equal to 0. The parameter NumHorVirtualBoundaries is derived as follows:

NumHorVirtualBoundaries = 0 if( sps_virtual_boundaries_enabled_flag )  NumHorVirtualBoundaries = sps_virtual_boundaries_present_flag ?   sps_num_hor_virtual_boundaries : (86)   ph_num_hor_virtual_boundaries When sps_virtual_boundaries_enabled_flag is equal to 1 and ph_virtual_boundaries_present_flag is equal to 1, the sum of ph_num_ver_virtual_boundaries and ph_num_hor_virtual_boundaries shall be greater than 0. ph_virtual_boundaries_pos_y[i] specifies the location of the i-th horizontal virtual boundary in units of luma samples divided by 8. The value of ph_virtual_boundaries_pos_y[i] shall be in the range of 1 to Ceil(pic_height_in_luma_samples+8)−1, inclusive. The list VirtualBoundariesPosY[i] for i ranging from 0 to NumHorVirtualBoundaries−1, inclusive, in units of luma samples, specifying the locations of the horizontal virtual boundaries, is derived as follows:

for( i = 0; i < NumHorVirtualBoundaries; i++)  VirtualBoundariesPosY[ i ] = ( sps_virtual_boundaries_present_flag ?  sps_virtual_boundaries_pos_y[ i ] : (87)  ph_virtual_boundaries_pos_y[ i ] ) * 8 The distance between any two horizontal virtual boundaries shall be greater than or equal to CtbSizeY luma samples. pic_output_flag affects the decoded picture output and removal processes as specified in Annex C. When pic_output_flag is not present, it is inferred to be equal to 1. partition_constraints_override_flag equal to 1 specifies that partition constraint parameters are present in the PH. partition_constraints_override_flag equal to 0 specifies that partition constraint parameters are not present in the PH. When not present, the value of partition_constraints_override_flag is inferred to be equal to 0. ph_log2_diff_min_qt_min_cb_intra_slice_luma specifies the difference between the base 2 logarithm of the minimum size in luma samples of a luma leaf block resulting from quadtree splitting of a CTU and the base 2 logarithm of the minimum coding block size in luma samples for luma CUs in the slices with slice_type equal to 2 (I) associated with the PH. The value of ph_log2_diff_min_qt_min_cb_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. When not present, the value of ph_log2_diff_min_qt_min_cb_luma is inferred to be equal to sps_log2_diff_min_qt_min_cb_intra_slice_luma. ph_max_mtt_hierarchy_depth_intra_slice_luma specifies the maximum hierarchy depth for coding units resulting from multi-type tree splitting of a quadtree leaf in slices with slice_type equal to 2 (I) associated with the PH. The value of ph_max_mtt_hierarchy_depth_intra_slice_luma shall be in the range of 0 to 2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive. When not present, the value of ph_max_mtt_hierarchy_depth_intra_slice_luma is inferred to be equal to sps_max_mtt_hierarchy_depth_intra_slice_luma. ph_log2_diff_max_bt_min_qt_intra_slice_luma specifies the difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a luma coding block that can be split using a binary split and the minimum size (width or height) in luma samples of a luma leaf block resulting from quadtree splitting of a CTU in slices with slice_type equal to 2 (I) associated with the PH. The value of ph_log2_diff_max_bt_min_qt_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeIntraY, inclusive. When not present, the value of ph_log2_diff_max_bt_min_qt_intra_slice_luma is inferred to be equal to sps_log2_diff_max_bt_min_qt_intra_slice_luma. ph_log2_diff_max_tt_min_qt_intra_slice_luma specifies the difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a luma coding block that can be split using a ternary split and the minimum size (width or height) in luma samples of a luma leaf block resulting from quadtree splitting of a CTU in slices with slice_type equal to 2 (I) associated with the PH. The value of ph_log2_diff_max_tt_min_qt_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeIntraY, inclusive. When not present, the value of ph_log2_diff_max_tt_min_qt_intra_slice_luma is inferred to be equal to sps_log2_diff_max_tt_min_qt_intra_slice_luma. ph_log2_diff_min_qt_min_cb_intra_slice_chroma specifies the difference between the base 2 logarithm of the minimum size in luma samples of a chroma leaf block resulting from quadtree splitting of a chroma CTU with treeType equal to DUAL_TREE_CHROMA and the base 2 logarithm of the minimum coding block size in tuna samples for chroma CUs with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) associated with the PH. The value of ph_log2_diff_min_qt_min_cb_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. When not present, the value of ph_log2_diff_min_qt_min_cb_intra_slice_chroma is inferred to be equal to sps_log2_diff_min_qt_min_cb_intra_slice_chroma. ph_max_mtt_hierarchy_depth_intra_slice_chroma specifies the maximum hierarchy depth for chroma coding units resulting from multi-type tree splitting of a chroma quadtree leaf with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) associated with the PH. The value of ph_max_mtt_hierarchy_depth_intra_slice_chroma shall be in the range of 0 to 2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive. When not present, the value of ph_max_mtt_hierarchy_depth_intra_slice_chroma is inferred to be equal to sps_max_mtt_hierarchy_depth_intra_slice_chroma. ph_log2_diff_max_bt_min_qt_intra_slice_chroma specifies the difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a chroma coding block that can be split using a binary split and the minimum size (width or height) in luma samples of a chroma leaf block resulting from quadtree splitting of a chroma CTU with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) associated with the PH. The value of ph_log2_diff_max_bt_min_qt_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeIntraC, inclusive. When not present, the value of ph_log2_diff_max_bt_min_qt_intra_slice_chroma is inferred to be equal to sps_log2_diff_max_bt_min_qt_intra_slice_chroma. ph_log2_diff_max_tt_min_qt_intra_slice_chroma specifies the difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a chroma coding block that can be split using a ternary split and the minimum size (width or height) in luma samples of a chroma leaf block resulting from quadtree splitting of a chroma CTU with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) associated with the PH. The value of ph_log2_diff_max_tt_min_qt_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeIntraC, inclusive. When not present, the value of ph_log2_diff_max_tt_min_qt_intra_slice_chroma is inferred to be equal to sps_log2_diff_max_tt_min_qt_intra_slice_chroma ph_cu_qp_delta_subdiv_intra_slice specifies the maximum cbSubdiv value of coding units in intra slice that convey cu_qp_delta_abs and cu_qp_delta_sign_flag. The value of ph_cu_qp_delta_subdiv_intra_slice shall be in the range of 0 to 2*(CtbLog2SizeY−MinQtLog2SizeIntraY+ph_max_mtt_hierarchy_depth_intra_slice_luma), inclusive. When not present, the value of ph_cu_qp_delta_subdiv_intra_slice is inferred to be equal to 0. ph_cu_chroma_qp_offset_subdiv_intra_slice specifies the maximum cbSubdiv value of coding units in intra slice that convey cu_chroma_qp_offset_flag. The value of ph_cu_chroma_qp_offset_subdiv_intra_slice shall be in the range of 0 to 2*(CtbLog2SizeY−MinQtLog2SizeIntraY+ph_max_mtt_hierarchy_depth_intra_slice_luma), inclusive. When not present, the value of ph_cu_chroma_qp_offset_subdiv_intra_slice is inferred to be equal to 0. ph_log2_diff_min_qt_min_cb_inter_slice specifies the difference between the base 2 logarithm of the minimum size in luma samples of a luma leaf block resulting from quadtree splitting of a CTU and the base 2 logarithm of the minimum luma coding block size in luma samples for luma CUs in the slices with slice_type equal to 0 (B) or 1 (P) associated with the PH. The value of ph_log2_diff_min_qt_min_cb_inter_slice shall be in the range of 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. When not present, the value of ph_log2_diff_min_qt_min_cb_luma is inferred to be equal to sps_log2_diff_min_qt_min_cb_inter_slice. ph_max_mtt_hierarchy_depth_inter_slice specifies the maximum hierarchy depth for coding units resulting from multi-type tree splitting of a quadtree leaf in slices with slice_type equal to 0 (B) or 1 (P) associated with the PH. The value of ph_max_mtt_hierarchy_depth_inter_slice shall be in the range of 0 to 2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive. When not present, the value of ph_max_mtt_hierarchy_depth_inter_slice is inferred to be equal to sps_max_mtt_hierarchy_depth_inter_slice. ph_log2_diff_max_bt_min_qt_inter_slice specifies the difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a luma coding block that can be split using a binary split and the minimum size (width or height) in luma samples of a luma leaf block resulting from quadtree splitting of a CTU in the slices with slice_type equal to 0 (B) or 1 (P) associated with the PH. The value of ph_log2_diff_max_bt_min_qt_inter_slice shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeInterY, inclusive. When not present, the value of ph_log2_diff_max_bt_min_qt_inter_slice is inferred to be equal to sps_log2_diff_max_bt_min_qt_inter_slice. ph_log2_diff_max_tt_min_qt_inter_slice specifies the difference between the base 2 logarithm of the maximum size (width or height) in luma samples of a luma coding block that can be split using a ternary split and the minimum size (width or height) in luma samples of a luma leaf block resulting from quadtree splitting of a CTU in slices with slice_type equal to 0 (B) or 1 (P) associated with the PH. The value of ph_log2_diff_max_tt_min_qt_inter_slice shall be in the range of 0 to CtbLog2SizeY−MinQtLog2SizeInterY, inclusive. When not present, the value of ph_log2_diff_max_tt_min_qt_inter_slice is inferred to be equal to sps_log2_diff_max_tt_min_qt_inter_slice. ph_cu_qp_delta_subdiv_inter_slice specifies the maximum cbSubdiv value of coding units that in inter slice convey cu_qp_delta_abs and cu_qp_delta_sign_flag. The value of ph_cu_qp_delta_subdiv_inter_slice shall be in the range of 0 to 2*(CtbLog2SizeY−MinQtLog2SizeInterY+ph_max_mtt_hierarchy_depth_inter_slice), inclusive. When not present, the value of ph_cu_qp_delta_subdiv_inter_slice is inferred to be equal to 0. ph_cu_chromes_qp_offset_subdiv_inter_slice specifies the maximum cbSubdiv value of coding units in inter slice that convey cu_chroma_qp_offset_flag. The value of ph_cu_chroma_qp_offset_subdiv_inter_slice shall be in the range of 0 to 2*(CtbLog2SizeY−MinQtLog2SizeInterY+ph_max_mtt_hierarchy_depth_inter_slice), inclusive. When not present, the value of ph_cu_chroma_qp_offset_subdiv_inter_slice is inferred to be equal to 0. ph_temporal_mvp_enabled_flag specifies whether temporal motion vector predictors can be used for inter prediction for slices associated with the PH. If ph_temporal_mvp_enabled_flag is equal to 0, the syntax elements of the slices associated with the PH shall be constrained such that no temporal motion vector predictor is used in decoding of the slices. Otherwise (ph_temporal_mvp_enabled_flag is equal to 1), temporal motion vector predictors may be used in decoding of the slices associated with the PH. When not present, the value of ph_temporal_mvp_enabled_flag is inferred to be equal to 0. When no reference picture in the DPB has the same spatial resolution as the current picture. the value of ph_temporal_mvp_enabled_flag shall be equal to 0. The maximum number of subblock-based merging MVP candidates, MaxNumSubblockMergeCand, is derived as follows:

if( sps_affine_enabled_flag )  MaxNumSubblockMergeCand = 5 − (88)  five_minus_max_num_subblock_merge_cand else  MaxNumSubblockMergeCand = sps_sbtmvp_enabled_flag &&  ph_temporal_mvp_enable_flag The value of MaxNumSubblockMergeCand shall be in the range of 0 to 5, inclusive. ph_collocated_from_l0_flag equal to 1 specifies that the collocated picture used for temporal motion vector prediction is derived from reference picture list 0. ph_collocated_from_l0_flag equal to 0 specifies that the collocated picture used for temporal motion vector prediction is derived from reference picture list 1. ph_collocated_ref_idx specifies the reference index of the collocated picture used for temporal motion vector prediction. When ph_collocated_from_l0_flag is equal to 1, ph_collocated_ref_idx refers to an entry in reference picture list 0, and the value of ph_collocated_ref_idx shall be in the range of 0 to num_ref_entries[0][RplsIdx[0]]−1, inclusive. When ph_collocated_from_l0_flag is equal to 0, ph_collocated_ref_idx refers to an entry in reference picture list 1, and the value of ph_collocated_ref_idx shall be in the range of 0 to num_ref_entries[1][RplsIdx[1]]−1, inclusive. When not present, the value of ph_collocated_ref_idx is inferred to be equal to 0. mvd_l1_zero_flag equal to 1 indicates that the mvd_coding(x0, y0, 1) syntax structure is not parsed and MvdL1[x0][y0][compIdx] and MvdCpL1[x0][y0][cpIdx][compIdx] are set equal to 0 for compIdx=0 . . . 1 and cpIdx=0 . . . 2. mvd_l1_zero_flag equal to 0 indicates that the mvd_coding(x0, y0, 1) syntax structure is parsed. ph_fpel_mmvd_enabled_flag equal to 1 specifies that merge mode with motion vector difference uses integer sample precision in the slices associated with the PH. ph_fpel_mmvd_enabled_flag equal to 0 specifies that merge mode with motion vector difference can use fractional sample precision in the slices associated with the PH. When not present, the value of ph_fpel_mmvd_enabled_flag is inferred to be 0. ph_disable_bdof_flag equal to 1 specifies that bi-directional optical flow inter prediction based inter bi-prediction is disabled in the slices associated with the PH. ph_disable_bdof_flag equal to 0 specifies that bi-directional optical flow inter prediction based inter bi-prediction may or may not be enabled in the slices associated with the PH. When ph_disable_bdof_flag is not present, the following applies:

-   -   If sps_bdof_enabled_flag is equal to 1, the value of         ph_disable_bdof_flag is inferred to be equal to 0.     -   Otherwise (sps_bdof_enabled_flag is equal to 0), the value of         ph_disable_bdof_flag is inferred to be equal to 1.         ph_disable_dmvr_flag equal to 1 specifies that decoder motion         vector refinement based inter bi-prediction is disabled in the         slices associated with the PH. ph_disable_dmvr_flag equal to 0         specifies that decoder motion vector refinement based inter         bi-prediction may or may not be enabled in the slices associated         with the PH.         When ph_disable_dmvr_flag is not present, the following applies:     -   If sps_dmvr_enabled_flag is equal to 1, the value of         ph_disable_dmvr_flag is inferred to be equal to 0.     -   Otherwise (sps_dmvr_enabled_flag is equal to 0), the value of         ph_disable_dmvr_flag is inferred to be equal to 1.         ph_disable_prof_flag equal to 1 specifies that prediction         refinement with optical flow is disabled in the slices         associated with the PH. ph_disable_prof_flag equal to 0         specifies that prediction refinement with optical flow may or         may not be enabled in the slices associated with the PH.         When ph_disable_prof_flag is not present, the following applies:     -   If sps_affine_prof_enabled_flag is equal to 1, the value of         ph_disable_prof_flag is inferred to be equal to 0.     -   Otherwise (sps_affine_prof_enabled_flag is equal to 0), the         value of ph_disable_prof_flag is inferred to be equal to 1.         ph_qp_delta specifies the initial value of Qp_(Y) to be used for         the coding blocks in the picture until modified by the value of         CuQpDeltaVal in the coding unit layer.         When qp_delta_info_in_ph_flag is equal to 1, the initial value         of the Qp_(Y) quantization parameter for all slices of the         picture, SliceQpy, is derived as follows:

SliceQp_(Y)=26+init_qp_minus26+ph_qp_delta  (89)

The value of SliceQp_(Y) shall be in the range of −QpBdOffset to +63, inclusive. ph_joint_cbcr_sign_flag specifies whether, in transform units with tu_joint_cbcr_residual_flag[x0][y0] equal to 1, the collocated residual samples of both chroma components have inverted signs. When tu_joint_cbcr_residual_flag[x0][y0] equal to 1 for a transform unit, ph_joint_cbcr_sign_flag equal to 0 specifies that the sign of each residual sample of the Cr (or Cb) component is identical to the sign of the collocated Cb (or Cr) residual sample and ph_joint_cbcr_sign_flag equal to 1 specifies that the sign of each residual sample of the Cr (or Cb) component is given by the inverted sign of the collocated Cb (or Cr) residual sample. ph_sao_luma_enabled_flag equal to 1 specifies that SAO is enabled for the luma component in all slices associated with the PH; ph_sao_luma_enabled_flag equal to 0 specifies that SAO for the luma component may be disabled for one, or more, or all slices associated with the PH. When ph_sao_luma_enabled_flag is not present, it is inferred to be equal to 0. ph_sao_chroma_enabled_flag equal to 1 specifies that SAO is enabled for the chroma component in all slices associated with the PH; ph_sao_chroma_enabled_flag equal to 0 specifies that SAO for chroma component may be disabled for one, or more, or all slices associated with the PH. When ph_sao_chroma_enabled_flag is not present, it is inferred to be equal to 0. ph_dep_quant_enabled_flag equal to 0 specifies that dependent quantization is disabled for the current picture. ph_dep_quant_enabled_flag equal to 1 specifies that dependent quantization is enabled for the current picture. When ph_dep_quant_enabled_flag is not present, it is inferred to be equal to 0. pic_sign_data_hiding_enabled_flag equal to 0 specifies that sign bit hiding is disabled for the current picture. pic_sign_data_hiding_enabled_flag equal to 1 specifies that sign bit hiding is enabled for the current picture. When pic_sign_data_hiding_enabled_flag is not present, it is inferred to be equal to 0. ph_deblocking_filter_override_flag equal to 1 specifies that deblocking parameters are present in the PH. ph_deblocking_filter_override_flag equal to 0 specifies that deblocking parameters are not present in the PH. When not present, the value of ph_deblocking_filter_override_flag is inferred to be equal to 0. ph_deblocking_filter_disabled_flag equal to 1 specifies that the operation of the deblocking filter is not applied for the slices associated with the PH. ph_deblocking_filter_disabled_flag equal to 0 specifies that the operation of the deblocking filter is applied for the slices associated with the PH. When ph_deblocking_filter_disabled_flag is not present, it is inferred to be equal to pps_deblocking_filter_disabled_flag. ph_beta_offset_div2 and ph_tc_offset_div2 specify the deblocking parameter offsets for β and tC (divided by 2) that are applied to the luma component for the slices associated with the PH. The values of ph_beta_offset_div2 and ph_tc_offset_div2 shall both be in the range of −12 to 12, inclusive. When not present, the values of ph_beta_offset_div2 and ph_tc_offset_div2 are inferred to be equal to pps_beta_offset_div2 and pps_tc_offset_div2, respectively. ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 specify the deblocking parameter offsets for β and tC (divided by 2) that are applied to the Cb component for the slices associated with the PH. The values of ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 shall both be in the range of −12 to 12, inclusive. When not present, the values of ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 are inferred to be equal to pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2, respectively. ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 specify the deblocking parameter offsets for β and tC (divided by 2) that are applied to the Cr component for the slices associated with the PH. The values of ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 shall both be in the range of −12 to 12, inclusive. When not present, the values of ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 are inferred to be equal to pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2, respectively. ph_extension_length specifies the length of the PH extension data in bytes. not including the bits used for signalling ph_extension_length itself. The value of ph_extension_length shall be in the range of 0 to 256, inclusive. When not present, the value of ph_extension_length is inferred to be equal to 0. ph_extension_data_byte may have any value. Decoders conforming to this version of this Specification shall ignore the value of ph_extension_data_byte. Its value does not affect decoder conformance to profiles specified in this version of specification.

3.9. SH Syntax and Semantics

In the latest WC draft text, the SH syntax and semantics are as follows:

slice_header( ) { Descriptor  picture_header_in_slice_header_flag  u (1)  if( picture_header_in_slice_header_flag )   picture_header_structure( )  if( subpic_info_present_flag )   slice_subpic_id  u (v)  if( (rect_slice_flag && NumSlicesInSubpic[ CurrSubpicldx ] > 1 ) ∥    ( !rect_slice_flag && NumTilesInPic > 1 ) )   slice_address  u (v)  for( i = 0; i < NumExtraShBits; i++ )   sh_extra_bit[ i ]  u (1)  if( !rect_slice_flag && NumTilesInPic > 1 )   num_tiles_in_slice_minus1 ue (v)  if( ph_inter_slice_allowed_flag )   slice_type ue (v)  if( sps_alf_enabled_flag && !alf_info_in_ph_flag ) {   slice_alf_enabled_flag  u (1)   if( slice_alf_enabled_flag ) {    slice_num_alf_aps_ids_luma  u (3)    for i = 0; i < slice_num_alf_aps_ids_luma; i++ )     slice_alf_aps_id_luma[ i ]  u (3)    if( ChromaArrayType != 0 )     slice_alf_chroma_idc  u (2)    iff slice_alf_chroma_idc )     slice_alf_aps_id_chroma  u (3)    if( sps_ccalf_enabled_flag ) {     slice_cc_alf_cb_enabled_flag  u (1)     if( slice_cc_alf_cb_enabled_flag )      slice_cc_alf_ch_aps_id  u (3)     slice_cc_alf_er_enabled_flag  u (1)     if( slice_cc_alf_cr_enabled_flag )      slice_cc_alf_cr_aps_id  u (3)    }   }  }  if( separate_colour_plane_flag = = 1 )   colour_plane_id  u (2)  if( ( !rpl_info_in_ph_flag && ( (nal_unit_type = IDR_W_RADL && nal_unit_type !=    IDR_N_LP ) ∥ sps_idr_rpl_present_flag ) )   ref_pic_lists( )  if( ( rpl_info_in_ph_flag ∥ ( ( nal_unit_type != IDR_W_RADL && nal_unit_type !=    IDR_N_LP ) ∥ sps_idr_rpl_present_flag ) ) &&    ( slice_type != I && num_ref_entries[ 0 ][ RplsIdx[ 0 ] ] > 1) ∥    ( slice_type = = B && num_ref_entries[ 1 ][ RplsIdx[ 1 ] ] > 1 ) ) {   num_ref_idx_active_override_flag  u (1)   if( num_ref_idx_active_override_flag )    for( i = 0; i < ( slice_type = = B ? 2 : 1); i++ )     if( num_ref_entries[ i ][ RplsIdx[ i ] ] > 1 )      num_ref_idx_active_minus1[ i ] ue (v)  }  if( slice_type != I ) {   if( cabac_init_present_flag )    cabac_init_flag  u (1)   if( ph_temporal_mvp_enabled_flag && !rpl_info_in_ph_flag ) {    if( slice_type = = B )     slice_collocated_from_l0_flag  u (1)   if( ( slice_collocated_from_l0_flag && NumRefIdxActive[ 0 ] > 1 ) ∥      ( ! slice_collocated_from_l0_flag && NumRefIdxActive [ 1 ] > 1) )     slice_collocated_ref_idx ue (v)   }   if( !wp_info_in_ph_flag && ( ( pps_weighted_pred_flag && slice_type == P ) ∥     ( pps_weighted_bipred_flag && slice_type = = B ) ) )    pred_weight_table( )  }  if( !qp_delta_info_in_ph_flag )   slice_gp_delta se (v)  if( pps_slice_chroma_qp_offsets_present_flag ) {   slice_cb_qp_offset se (v)   slice_cr_qp_offset se (v)   if( sps_joint_cbcr_enabled_flag )    slice_joint_cbcr_qp_offset se (v)  }  if( pps_cu_chroma_qp_offset_list_enabled_flag )   cu_chroma_gp_offset_enabled_flag  u (1)  if( sps_sao_enabled_flag && !sao_info_in_ph_flag ) {   slice_sao_luma_flag  u (1)   if( ChromaArrayType != 0 )    slice_sao_chroma_flag  u (1)  }  if( deblocking_filter_override_enabled_flag && !dbf_info_in_ph_flag )   slice_deblocking_filter_override_flag  u (1)  if( slice_deblocking_filter_override_flag ) {   slice_deblocking_filter_disabled_flag  u (1)   if( !slice_deblocking_filter_disabled_flag ) {    slice_beta_offset_div2 se (v)    slice_tc_offset_div2 se (v)    slice_cb_beta_offset_div2 se (v)    slice_cb_tc_offset_div2 se (v)    slice_cr_beta_offset_div2 se (v)    slice_cr_tc_offset_div2 se (v)   }  }  slice_ts_residual_coding_disabled_flag  u (1)  if( ph_lmcs_enabled_flag )   slice_lmcs_enabled_flag  u (1)  if( ph_scaling_list_enabled_flag )   slice_scaling_list_present_flag  u (1)  if( NumEntryPoints > 0 ) {   offset_len_minus1 ue (v)   for( i = 0; i < NumEntryPoints; i++ )    entry_point_offset_minus1[ i ]  u (v)  }  if( slice_header_extension_present_flag ) {   slice_header_extension_length ue (v)   for i = 0; i < slice_header_extension_length; i++ )    slice_header_extension_data_byte[ i ]  u (8)  }  byte_alignment( ) } The variable CuQpDeltaVal, specifying the difference between a lama quantization parameter for the coding unit containing cu_qp_delta_abs and its prediction, is set equal to 0. The variables CuQpOffset_(Cb), CuQpOffset_(Cr), and CuQpOffset_(CbCr), specifying values to be used when determining the respective values of the Qp′_(Cb), Qp′_(Cr), and Qp′_(CbCr), quantization parameters for the coding unit containing cu_chroma_qp_offset_flag, are all set equal to 0. picture_header_in_slice_header_flag equal to 1 specifies that the PH syntax structure is present in the slice header. picture_header_in_slice_header_flag equal to 0 specifies that the PH syntax structure is not present in the slice header. It is a requirement of bitstream conformance that the value of picture_header_in_slice_header_flag shall be the same in all coded slices in a CLVS. When picture_header_in_slice_header_flag is equal to 1 for a coded slice, it is a requirement of bitstream conformance that no VCL NAL unit with nal_unit_type equal to PH_NUT shall be present in the CLVS. When picture_header_in_slice_header_flag is equal to 0, all coded slices in the current picture shall have picture_header_in_slice_header_flag is equal to 0, and the current PU shall have a PH NAL unit. slice_subpic_id specifies the subpicture ID of the subpicture that contains the slice. if slice_subpic_id is present, the value of the variable CurrSubpicIdx is derived to be such that SubpicIdVal[CurrSubpicIdx] is equal to slice_subpic_id. Otherwise (slice_subpic_id is not present), CurrSubpicIdx is derived to be equal to 0. The length of slice_subpic_id is sps_subpic_id_len_minus1+1 bits. slice_address specifies the slice address of the slice. When not present, the value of slice_address is inferred to be equal to 0. When rect_slice_flag is equal to 1 and NumSlicesInSubpic[CurrSubpicIdx] is equal to 1, the value of slice_address is inferred to be equal to 0. If rect_slice_flag is equal to 0, the following applies:

-   -   The slice address is the raster scan tile index.     -   The length of slice_address is Ceil(Log2 (NumTilesInPic)) bits.     -   The value of slice_address shall be in the range of 0 to         NumTilesInPic−1, inclusive.         Otherwise (rect_slice_flag is equal to 1), the following         applies:     -   The slice address is the subpicture-level slice index of the         slice.     -   The length of slice_address is         Ceil(Log2(NumSlicesInSubpic[CurrSubpicIdx])) bits.     -   The value of slice_address shall be in the range of 0 to         NumSlicesInSubpic[CurrSubpicIdx]−1, inclusive.         It is a requirement of bitstream conformance that the following         constraints apply:     -   If rect_slice_flag is equal to 0 or subpic_info_present_flag is         equal to 0, the value of slice_address shall not be equal to the         value of slice_address of any other coded slice NAL unit of the         same coded picture.     -   Otherwise, the pair of slice_subpic_id and slice_address values         shall not be equal to the pair of slice_subpic_id and         slice_address values of any other coded slice NAL unit of the         same coded picture.     -   The shapes of the slices of a picture shall be such that each         CTU, when decoded, shall have its entire left boundary and         entire top boundary consisting of a picture boundary or         consisting of boundaries of previously decoded CTU(s).         sh_extra_bit[i] may be equal to 1 or 0. Decoders conforming to         this version of this Specification shall ignore the value of         sh_extna_bit[i]. Its value does not affect decoder conformance         to profiles specified in this version of specification.         num_tiles_in_slice_minus1 plus 1, when present, specifies the         number of tiles in the slice. The value of         num_tiles_in_slice_minus1 shall be in the range of 0 to         NumTilesInPic−1, inclusive. The variable NumCtusInCurrSlice,         which specifies the number of CTUs in the current slice, and the         list CtbAddrInCurrSlice[i], for i ranging from 0 to         NumCtusInCurrSlice−1, inclusive, specifying the picture raster         scan address of the i-th CTB within the slice, are derived as         follows:

if( rect_slice_flag ) {  picLevelSliceIdx = slice_address  for( j = 0; j < CurrSubpicIdx; j++ )   picLevelSliceIdx += NumSlicesInSubpic[ j ]  NumCtusInCurrSlice = NumCtusInSlice[ picLevelSliceIdx ]  for( i = 0; i < NumCtusInCurrSlice; i++ )   CtbAddrInCurrSlice[ i ] = CtbAddrInSlice[ (117)   picLevelSliceIdx ][ i ]  } else {  NumCtusInCurrSlice = 0  for( tileIdx = slice_address; tileIdx <= slice_address + num_tiles_in_slice_minus1; tileIdx++ ) {   tileX = tileIdx % NumTileColumns   tileY = tileIdx / NumTileColumns   for( ctbY = tileRowBd[ tileY ]; ctbY < tileRowBd[ tileY + 1 ];   ctbY++ ) {    for( ctbX = tileColBd[ tileX ]; ctbX < tileColBd[ tileX + 1 ];    ctbX++ ) {     CtbAddrInCurrSlice[ NumCtusInCurrSlice ] = ctbY *     PicWidthInCtb + ctbX     NumCtusInCurrSlice++    }   }  } } The variables SubpicLeftBoundaryPos, SubpicTopBoundaryPos, SubpicRightBoundaryPos, and SubpicBotBoundaryPos are derived as follows:

if( subpic_treated_as_pic_flag[ CurrSubpicIdx ] ) {  SubpicLeftBoundaryPos = subpic_ctu_top_left_x[  CurrSubpicIdx ] * CtbSizeY  SubpicRightBoundaryPos = Min(  pic_width_max_in_luma_samples − 1,   ( subpic_ctu_top_left_x[ CurrSubpicIdx ] +   subpic_width_minus1[ CurrSubpicIdx ] + 1 ) * CtbSizeY − 1 )  SubpicTopBoundaryPos = subpic_ctu_top_left_y[ (118)  CurrSubpicIdx ] *CtbSizeY  SubpicBotBoundaryPos = Min(  pic_height_max_in_luma_samples − 1,   ( subpic_ctu_top_left_y[ CurrSubpicIdx ] +   subpic_height_minus1[ CurrSubpicIdx ] + 1 ) * CtbSizeY − 1 ) } slice_type specifies the coding type of the slice according to Table 9.

TABLE 9 Name association to slice_type slice_type Name of slice_type 0 B (B slice) 1 P (P slice) 2 I (1 slice) When not present, the value of slice_type is inferred to be equal to 2. When ph_intra_slice_allowed_flag is equal to 0, the value of slice_type shall be equal to 0 or 1. When nal_unit_type in the range of IDR_W_RADL to CRA_NUT, inclusive, and vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1, slice_type shall be equal to 2. The variables MinQtLog2SizeY, MinQtLog2SizeC, MinQtSizeY, MinQtSizeC, MaxBtSizeY, MaxBtSizeC, MinBtSizeY, MaxTtSizeY, MaxTtSizeC, MinTtSizeY, MaxMttDepthY and MaxMttDepthC are derived as follows:

-   -   If slice_type equal to 2 (I), the following applies:

MinQtLog2SizeY=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_luma  (119)

MinQtLog2SizeC=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_chroma  (120)

MaxBtSizeY=1<<(MinQtLog2SizeY+ph_log2_diff_max_bt_min_qt_intra_slice_luma)  (121)

MaxBtSizeC=1<<(MinQtLog2SizeC+ph_log2_diff_max_bt_min_qt_intra_slice_chroma)  (122)

MaxTtSizeY=1<<(MinQtLog2SizeY+ph_log2_diff_max_tt_min_qt_intra_slice_luma)  (123)

MaxTtSizeC=1<<(MinQtLog2SizeC+ph_log2_diff_max_tt_min_qt_intra_slice_chroma)  (124)

MaxMttDepthY=ph_max_mtt_hierarchy_depth_intra_slice_luma  (125)

MaxMttDepthC=ph_max_mtt_hierarchy_depth_intra_slice_chroma  (126)

CuQpDeltaSubdiv=ph_cu_qp_delta_subdiv_intra_slice  (127)

CuChromaQpOffsetSubdiv=ph_cu_chroma_qp_offset_subdiv_intra_slice  (128)

-   -   Otherwise (slice_type equal to 0 (B) or 1 (P)), the following         applies:

MinQtLog2SizeY=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_inter_slice  (129)

MinQtLog2SizeC=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_inter_slice  (130)

MaxBtSizeY=1<<(MinQtLog2SizeY+ph_log2_diff_max_bt_min_qt_inter_slice)  (131)

MaxBtSizeC=1<<(MinQtLog2SizeC+ph_log2_diff_max_bt_min_qt_inter_slice)  (132)

MaxTtSizeY=1<<(MinQtLog2SizeY+ph_log2_diff_max_tt_min_qt_inter_slice)  (133)

MaxTtSizeC=1<<(MinQtLog2SizeC+ph_log2_diff_max_tt_min_qt_inter_slice)  (134)

MaxMttDepthY=ph_max_mtt_hierarchy_depth_inter_slice  (135)

MaxMttDepthC=ph_max_mtt_hierarchy_depth_inter_slice  (136)

CuQpDeltaSubdiv=ph_cu_qp_delta_subdiv_inter_slice  (137)

CuChromaQpOffsetSubdiv=ph_cu_chroma_qp_offset_subdiv_inter_slice  (138)

-   -   The following applies:

MinQtSizeY=1<<MinQtLog2SizeY  (139)

MinQtSizeC=1<<MinQtLog2SizeC  (140)

MinBtSizeY=1<<MinCbLog2SizeY  (141)

MinTtSizeY=1<<MinCbLog2SizeY  (142)

slice_alf_enabled_flag equal to 1 specifies that adaptive loop filter is enabled and may be applied to Y, Cb, or Cr colour component in a slice. slice_alf_enabled_flag equal to 0 specifies that adaptive loop filter is disabled for all colour components in a slice. When not present, the value of slice_alf_enabled_flag is inferred to be equal to ph_alf_enabled_flag. slice_num_alf_aps_ids_luma specifies the number of ALF APSs that the slice refers to. When slice_alf_enabled_flag is equal to 1 and slice_num_alf_aps_ids_luma is not present, the value of slice_num_alf_aps_ids_luma is inferred to be equal to the value of ph_num_alf_aps_ids_luma. slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS that the luma component of the slice refers to. The TemporalId of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shall be less than or equal to the TemporalId of the coded slice NAL unit. When slice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is not present, the value of slice_alf_aps_id_luma[i] is inferred to be equal to the value of ph_alf_aps_id_luma[i]. The value of alf_luma_filter_signal_flag of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shall be equal to 1. slice_alf_chroma_idc equal to 0 specifies that the adaptive loop filter is not applied to Cb and Cr colour components. slice_alf_chroma_idc equal to 1 indicates that the adaptive loop filter is applied to the Cb colour component. slice_alf_chroma_idc equal to 2 indicates that the adaptive loop filter is applied to the Cr colour component. slice_alf_chroma_idc equal to 3 indicates that the adaptive loop filter is applied to Cb and Cr colour components. When slice_alf_chroma_idc is not present, it is inferred to be equal to ph_alf_chroma_idc. slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of the ALF APS that the chroma component of the slice refers to. The TemporalId of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_chroma shall be less than or equal to the TemporalId of the coded slice NAL unit. When slice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is not present, the value of slice_alf_aps_id_chroma is inferred to be equal to the value of ph_alf_aps_id_chroma. The value of alf_chroma_filter_signal_flag of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_chroma shall be equal to 1. slice_cc_alf_cb_enabled_flag equal to 0 specifics that the cross-component filter is not applied to the Cb colour component slice_cc_alf_cb_enabled_flag equal to 1 indicates that the cross-component filter is enabled and may be applied to the Cb colour component. When slice_cc_alf_cb_enabled_flag is not present, it is inferred to be equal to ph_cc_alf_cb_enabled_flag. slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id that the Cb colour component of the slice refers to. The TemporalId of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_id shall be less than or equal to the TemporalId of the coded slice NAL unit. When slice_cc_alf_cb_enabled_flag is equal to 1 and slice_cc_alf_cb_aps_id is not present, the value of slice_cc_alf_cb_aps_id is inferred to be equal to the value of ph_cc_alf_cb_aps_id. The value of alf_cc_cb_filter_signal_flag of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_id shall be equal to 1. slice_cc_alf_cr_enabled_flag equal to 0 specifies that the cross-component filter is not applied to the Cr colour component. slice_cc_alf_cb_enabled_flag equal to 1 indicates that the cross-component adaptive loop filter is enabled and may be applied to the Cr colour component. When slice_cc_alf_cr_enabled_flag is not present, it is inferred to be equal to ph_cc_alf_cr_enabled_flag. slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id that the Cr colour component of the slice refers to. The TemporalId of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id shall be less than or equal to the TemporalId of the coded slice NAL unit. When slice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id is not present, the value of slice_cc_alf_cr_aps_id is inferred to be equal to the value of ph_cc_alf_cr_aps_id. The value of alf_cc_cr_filter_signal_flag of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id shall be equal to 1. colour_plane_id identifies the colour plane associated with the current slice when separate_colour_plane_flag is equal to 1. The value of colour_plane_id shall be in the range of 0 to 2, inclusive. colour_plane_id values 0, 1 and 2 correspond to the Y, Cb and Cr planes, respectively. The value 3 of colour_plane_id is reserved for future use by ITU-T|ISO/IEC.

-   -   NOTE 1—There is no dependency between the decoding processes of         different colour planes of one picture.         num_ref_idx_active_override_flag equal to 1 specifies that the         syntax element num_ref_idx_active_minus1[0] is present for P and         B slices and the syntax element nunt_ref_idx_active_minus1[1] is         present for B slices. num_ref_idx_active_override_flag equal to         0 specifies that the syntax elements         num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1]         are not present. When not present, the value of         num_ref_idx_active_override_flag is inferred to be equal to 1.         num_ref_idx_active_minus1[i] is used for the derivation of the         variable NumRefIdxActive[i] as specified by Equation 143. The         value of num_ref_idx_active_minus1[i] shall be in the range of 0         to 14, inclusive.         For i equal to 0 or 1, when the current slice is a B slice,         num_ref_idx_active_override_flag is equal to 1, and         num_ref_idx_active_minus1[i] is not present,         num_ref_idx_active_minus1[i] is inferred to be equal to 0.         When the current slice is a P slice,         num_ref_idx_active_override_flag is equal to 1, and         num_ref_idx_active_minus1[0] is not present,         num_ref_idx_active_minus1[0] is inferred to be equal to 0.         The variable NumRefIdxActive[i] is derived as follows:

for( i = 0; i < 2; i++ ) {  if( slice_type = = B | | ( slice_type = = P && i = = 0 ) ) {   if( num_ref_idx_active_override_flag )    NumRefIdxActive[ i ] = (143)    num_ref_idx_active_minus1[ i ] + 1   else {    if( num_ref_entries[ i ][ RplsIdx[ i ] ] >=    num_ref_idx_default_active_minus1[ i ] + 1 )     NumRefIdxActive[ i ] =     num_ref_idx_default_active_minus1[ i ] + 1    else     NumRefIdxActive[ i ] = num_ref_entries[ i ][ RplsIdx[ i ] ]   }  } else /* slice_type = = I | | ( slice_type = = P && i = = 1 ) */   NumRefIdxActive[ i ] = 0 } The value of NumRefIdxActive[i]−1 specifies the maximum reference index for reference picture list i that may be used to decode the slice. When the value of NumRefIdxActive[i] is equal to 0, no reference index for reference picture list i may be used to decode the slice. When the current slice is a P slice, the value of NumRefIdcActive[0] shall be greater than 0. When the current slice is a B slice, both NumRefIdxActive[0] and NumRefIdxActive[1] shall be greater than 0. cabac_init_flag specifies the method for determining the initialization table used in the initialization process for context variables. When cabac_init_flag is not present, it is inferred to be equal to 0. slice_collocated_from_l0_flag equal to 1 specifies that the collocated picture used for temporal motion vector prediction is derived from reference picture list 0. slice_collocated_from_l0_flag equal to 0 specifies that the collocated picture used for temporal motion vector prediction is derived from reference picture list 1. When slice_type is equal to B or P, ph_temporal_mvp_enabled_flag is equal to 1, and slice_collocated_from_l0_flag is not present, the following applies:

-   -   If rpl_info_in_ph_flag is equal to 1,         slice_collocated_from_l0_flag is inferred to be equal to         ph_collocated_from_l0_flag.     -   Otherwise (rpl_info_in_ph_flag is equal to 0 and slice_type is         equal to P), the value of slice_collocated_from_l0_flag is         inferred to be equal to 1.         slice_collocated_ref_idx specifies the reference index of the         collocated picture used for temporal motion vector prediction.         When slice_type is equal to P or when slice_type is equal to B         and slice_collocated_from_l0_flag is equal to 1,         slice_collocated_ref_idx refers to an entry in reference picture         list 0, and the value of slice_collocated_ref_idx shall be in         the range of 0 to NumRefIdxActive[0]−1, inclusive.         When slice_type is equal to B and slice_collocated_from_l0_flag         is equal to 0, slice_collocated_ref_idx refers to an entry in         reference picture list 1, and the value of         slice_collocated_ref_idx shall be in the range of 0 to         NumRefIdxActive[1]−1, inclusive.         When slice_collocated_ref_idx is not present, the following         applies:     -   If rpl_info_in_ph_flag is equal to 1, the value of         slice_collocated_ref_idx is inferred to be equal to         ph_collocated_ref_idx.     -   Otherwise (rpl_info_in_ph_flag is equal to 0), the value of         slice_collocated_ref_idx is inferred to be equal to 0.         It is a requirement of bitstream conformance that the picture         referred to by slice_collocated_ref_idx shall be the same for         all slices of a coded picture.         It is a requirement of bitstream conformance that the values of         pic_width_in_luma_samples and pic_height_in_luma_samples of the         reference picture referred to by slice_collocated_ref_idx shall         be equal to the values of pic_width_in_luma_samples and         pic_height_in_luma_samples, respectively, of the current         picture, and         RprConstraintsActive[slice_collocated_from_l0_flag?0:1][slice_collocated_ref_idx]         shall be equal to 0.         slice_qp_delta specifies the initial value of Qp_(Y) to be used         for the coding blocks in the slice until modified by the value         of CuQpDeltaVal in the coding unit layer.         When qp_delta_info_in_ph_flag is equal to 0, the initial value         of the Qp_(Y) quantization parameter for the slice. SliceQpy, is         derived as follows:

SliceQp_(Y)=26+init_qp_minus26+slice_qp_delta  (144)

The value of SliceQp_(Y) shall be in the range of −QpBdOffset to +63, inclusive. When either of the following conditions is true:

-   -   The value of wp_info_in_ph_flag is equal to 1,         pps_weighted_pred_flag is equal to 1, and slice_type is equal to         P.     -   The value of wp_info_in_ph_flag is equal to 1,         pps_weighted_bipred_flag is equal to 1, and slice_type is equal         to B.         the following applies:     -   The value of NumRefIdxActive[0] shall be less than or equal to         the value of NumWeightsL0.     -   For each reference picture index RefPicList[0][i] for i in the         range of 0 to NumRefIdxActive[0]−1, inclusive, the luma weight.         Cb weight, and Cr weight that apply to the reference picture         index are LumaWeightL0[i], ChromaWeightL0[0][i], and         ChromaWeightL0[1][i], respectively.         When wp_info_in_ph_flag is equal to 1. pps_weighted_bipred_flag         is equal to 1, and slice_type is equal to B, the following         applies:     -   The value of NumRefIdxActive[1] shall be less than or equal to         the value of NumWeightsL1.     -   For each reference picture index RefPicList[1][i] for i in the         range of 0 to NumRefIdxActive[1]−1, inclusive, the luma weight,         Cb weight, and Cr weight that apply to the reference picture         index are LumaWeightL1[i], ChromaWeightL1[0][i], and         ChromaWeightL1[1][i], respectively.         slice_cb_qp_offset specifies a difference to be added to the         value of pps_cb_qp_offset when determining the value of the         Qp′_(Cb) quantization parameter. The value of slice_cb_qp_offset         shall be in the range of −12 to +12, inclusive. When         slice_cb_qp_offset is not present, it is inferred to be equal         to 0. The value of pps_cb_qp_offset+slice_cb_qp_offset shall be         in the range of −12 to +12, inclusive.         slice_cr_qp_offset specifies a difference to be added to the         value of pps_cr_qp_offset when determining the value of the         Qp′_(C), quantization parameter. The value of slice_cr_qp_offset         shall be in the range of −12 to +12, inclusive. When         slice_cr_qp_offset is not present, it is inferred to be equal         to 0. The value of pps_cr_qp_offset+slice_cr_qp_offset shall be         in the range of −12 to +12, inclusive.         slice_joint_cbcr_qp_offset specifies a difference to be added to         the value of pps_joint_cbcr_qp_offset_value when determining the         value of the Qp′_(CbCr). The value of slice joint_cbcr_qp_offset         shall be in the range of −12 to +12, inclusive. When         slice_joint_cbcr_qp_offset is not present, it is inferred to be         equal to 0. The value of         pps_joint_cbcr_qp_offset_value+slice_joint_cbcr_qp_offset shall         be in the range of −12 to +12, inclusive.         cu_chroma_qp_offset_enabled_flag equal to 1 specifies that the         cu_chroma_qp_offset_flag may be present in the transform unit         and palette coding syntax. cu_chroma_qp_offset_enabled_flag         equal to 0 specifies that the cu chroma_qp_offset_flag is not         present in the transform unit or palette coding syntax. When not         present, the value of cu_chroma_qp_offset_enabled_flag is         inferred to be equal to 0.         slice_sao_luma_flag equal to 1 specifies that SAO is enabled for         the liana component in the current slice; slice_sao_luma_flag         equal to 0 specifies that SAO is disabled for the luma component         in the current slice. When slice_sao_luma_flag is not present,         it is inferred to be equal to ph_sao_luma_enabled_flag.         slice_sao_chroma_flag equal to 1 specifies that SAO is enabled         for the chroma component in the current slice;         slice_sao_chroma_flag equal to 0 specifies that SAO is disabled         for the chroma component in the current slice. When         slice_sao_chroma_flag is not present, it is inferred to be equal         to ph_sao_chroma_enabled_flag.         slice_deblocking_filter_override_flag equal to 1 specifies that         deblocking parameters are present in the slice header.         slice_deblocking_filter_override_flag equal to 0 specifies that         deblocking parameters are not present in the slice header. When         not present, the value of slice_deblocking_filter_override_flag         is inferred to be equal to ph_deblocking_filter_override_flag.         slice_deblocking_filter_disabled_flag equal to 1 specifies that         the operation of the deblocking filter is not applied for the         current slice. slice_deblocking_filter_disabled_flag equal to 0         specifies that the operation of the deblocking filter is applied         for the current slice. When         slice_deblocking_filter_disabled_flag is not present, it is         inferred to be equal to ph_deblocking_filter_disabled_flag.         slice_beta_offset_div2 and slice_tc_offset_div2 specify the         deblocking parameter offsets for β and tC (divided by 2) that         are applied to the luma component for the current slice. The         values of slice_beta_offset_div2 and slice_tc_offset_div2 shall         both be in the range of −12 to 12, inclusive. When not present,         the values of slice_beta_offset_div2 and slice_tc_offset_div2         are inferred to be equal to ph_beta_offset_div2 and         ph_tc_offset_div2, respectively.         slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify         the deblocking parameter offsets for β and tC (divided by 2)         that are applied to the Cb component for the current slice. The         values of slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2         shall both be in the range of −12 to 12, inclusive. When not         present, the values of slice_cb_beta_offset_div2 and         slice_cb_tc_offset_div2 are inferred to be equal to         ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2, respectively.         slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify         the deblocking parameter offsets for β and tC (divided by 2)         that are applied to the Cr component for the current slice. The         values of slice_cr_beta_offset_div2 and slice_cr_tc_offset_div2         shall both be in the range of −12 to 12, inclusive. When not         present, the values of slice_cr_beta_offset_div2 and         slice_cr_tc_offset_div2 are inferred to be equal to         ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2, respectively.         slice_ts_residual_coding_disabled_flag equal to 1 specifies that         the residual_coding( ) syntax structure is used to parse the         residual samples of a transform skip block for the current         slice. slice_ts_residual_coding_disabled_flag equal to 0         specifies that the residual_ts_coding( ) syntax structure is         used to parse the residual samples of a transform skip block for         the current slice. When slice_ts_residual_coding_disabled_flag         is not present, it is inferred to be equal to 0.         slice_lmcs_enabled_flag equal to 1 specifies that luma mapping         with chroma scaling is enabled for the current slice.         slice_lmcs_enabled_flag equal to 0 specifies that luma mapping         with chroma scaling is not enabled for the current slice. When         slice_lmcs_enabled_flag is not present, it is inferred to be         equal to 0.         slice_scaling_list_present_flag equal to 1 specifies that the         scaling list data used for the current slice is derived based on         the scaling list data contained in the referenced scaling list         APS with aps_params_type equal to SCALING_APS and         adaptation_parameter_set_id equal to ph_scaling_list_aps_id.         slice_scaling_list_present_flag equal to 0 specifies that the         scaling list data used for the current picture is the default         scaling list data derived specified in clause 7.4.3.21. When not         present, the value of slice_scaling_list_present_flag is         inferred to be equal to 0.         The variable NumEntryPoints, which specifies the number of entry         points in the current slice, is derived as follows:

NumEntryPoints = 0 for( i = 1; i < NumCtusInCurrSlice; i++ ) {  ctbAddrX = CtbAddrInCurrSlice[ i ] % PicWidthInCtbsY  ctbAddrY = CtbAddrInCurrSlice[ i ] / PicWidthInCtbsY (145) prevCtbAddrX = CtbAddrInCurrSlice[ i − 1 ] % PicWidthInCtbsY  prevCtbAddrY = CtbAddrInCurrSlice[ i − 1 ] / PicWidthInCtbsY  if( CtbToTileRowBd[ ctbAddrY ] != CtbToTileRowBd[  prevCtbAddrY ] | |    CtbToTileColBd[ ctbAddrX ] != CtbToTileColBd[    prevCtbAddrX ] | |    ( ctbAddrY != prevCtbAddrY &&    sps_wpp_entry_point_offsets_present_flag ) )   NumEntryPoints++ } offset_len_minus1 plus 1 specifies the length, in bits. of the entrypoint_offset_minus1[i] syntax elements. The value of offset_len_minus1 shall be in the range of 0 to 31, inclusive. entry_point_offset_minus1[i] plus 1 specifies the i-th entry point offset in bytes, and is represented by offset_len_minus1 plus 1 bits. The slice data that follow the slice header consists of NumEntryPoints+1 subsets. with subset index values ranging from 0 to NumEntryPoints, inclusive. The first byte of the slice data is considered byte 0. When present, emulation prevention bytes that appear in the slice data portion of the coded slice NAL unit are counted as part of the slice data for purposes of subset identification. Subset 0 consists of bytes 0 to entry_point_offset_minus1[0], inclusive, of the coded slice data, subset k, with k in the range of 1 to NumEntryPoints−1, inclusive, consists of bytes firstByte[k] to lastByte[k], inclusive, of the coded slice data with firstByte[k] and lastByte[k] defined as:

firstByte[k]=entry_point_offset_minus1[n−1]+1)  (146)

lastByte[k]=firstByte[k]+entry_point_offset_minus1[k]  (147)

The last subset (with subset index equal to NumEntryPoints) consists of the remaining bytes of the coded slice data. When sps_entropy_coding_sync_enabled_flag is equal to 0 and the slice contains one or more complete tiles, each subset shall consist of all coded bits of all CTUs in the slice that are within the same tile, and the number of subsets (i.e., the value of NumEntryPoints+1) shall be equal to the number of tiles in the slice. When sps_entropy_coding_sync_enabled_flag is equal to 0 and the slice contains a subset of CTU rows from a single tile, the NumEntryPoints shall be 0, and the number of subsets shall be 1. The subset shall consist of all coded bits of all CTUs in the slice. When sps_entropy_coding_sync_enabled_flag is equal to 1, each subset k with k in the range of 0 to NumEntryPoints, inclusive, shall consist of all coded bits of all CTUs in a CTU row within a tile, and the number of subsets (i.e., the value of NumEntryPoints+1) shall be equal to the total number of tile-specific CTU rows in the slice. slice_header_extension_length specifies the length of the slice header extension data in bytes, not including the bits used for signalling slice_header_extension_length itself. The value of slice_header_extension_length shall be in the range of 0 to 256, inclusive. When not present, the value of slice_header_extension_length is inferred to be equal to 0. slice_header_extension_data_byte[i] may have any value. Decoders conforming to this version of this Specification shall ignore the values of all the slice_header_extension_data_byte[i] syntax elements. Its value does not affect decoder conformance to profiles specified in this version of specification.

3.10. Reference Picture Lists Syntax

In the latest WC draft text, the syntax structure ref_pic_lists( ) and semantics are as follows:

ref_pic_lists( ) { Descriptor  for( i = 0; i < 2; i++ ) {   if( num_ref_pic_lists_in_sps[ i ] > 0 &&      ( i = 0 ∥ i = 1 && rpl1_idx_present_flag ) ) )    rpl_sps_flag[ i ]  u (1)   if( rpl_sps_flag[ i ] ) {    if( num_ref_pic_lists_in_sps[ i ] > 1 &&       ( i = = 0 ∥ ( i = = 1 && rpl1_idx_present_flag ) ) )     rpl_idx[ i ]  u (v)   } else    ref_pic_list_struct( i, num_ref_pic_lists_in_sps[ i ] )   for( j = 0; j < NumLtrpEntries[ i ][RplsIdx[ i ] ]; j++ ) {    if( ltrp_in_header_flag[ i ][ RplsIdx[ i ] ] )     poc_lsb_lt i ] [ j ]  u (v)    delta_poc_msb_present_flag[ i ][ j ]  u (1)    if( delta_poc_msb_present_flag[ i ][ j ] )     delta_poc_msb_cycle_lt[ i ][ j ] ue (v)   }  } } The ref_pic_lists( ) syntax structure may be present in the PH syntax structure or the slice header. rpl_sps_flag[i] equal to 1 specifies that reference picture list i in ref_pic_lists( ) is derived based on one of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i in the SPS. rpl_sps_flag[i] equal to 0 specifies that reference picture list i of the picture is derived based on the ref_pic_list_struct(listIdx, rplsIdx) syntax structure with listIdx equal to i that is directly included in ref_pic_lists( ). When rpl_sps_flag[i] is not present, the following applies:

-   -   If num_ref_pic_lists_in_sps[i] is equal to 0, the value of         rpl_sps_flag[i] is inferred to be equal to 0.     -   Otherwise (num_ref_pic_lists_in_sps[i] is greater than 0), when         rpl1_idx_present_flag is equal to 0 and i is equal to 1, the         value of rpl_sps_flag[1] is inferred to be equal to         rpl_sps_flag[0].         rpl_idx[i] specifies the index, into the list of the         ref_pic_list_struct(listIdx, rplsIdx) syntax structures with         listIdx equal to i included in the SPS, of the         ref_pic_list_struct(listIdx, rplsIdx) syntax structure with         listIdx equal to i that is used for derivation of reference         picture list i of the current picture. The syntax element         rpl_idx[i] is represented by         Ceil(Log2(num_ref_pic_lists_in_sps[i])) bits. When not present,         the value of rpl_idx[i] is inferred to be equal to 0. The value         of rpl_idx[i] shall be in the range of 0 to         num_ref_pic_lists_in_sps[i]−1, inclusive. When rpl_sps_flag[i]         is equal to 1 and num_ref_pic_lists_in_sps[i] is equal to 1, the         value of rpl_idx[i] is inferred to be equal to 0. When         rpl_sps_flag[i] is equal to 1 and rpl1_idx_present_flag is equal         to 0, the value of rpl_idx[1] is inferred to be equal to         rpl_idx[0].         The variable RplsIdx[i] is derived as follows:

RplsIdx[i]=rpl_sps_flag[i]?rpl_idx[i]:num_ref_pic_lists_in_sps[i]  (149)

poc_lsb_lt[i][j] specifies the value of the picture order count modulo MaxPicOrderCntLsb of the j-th LTRP entry in the i-th reference picture list in the ref_pic_lists( ) syntax structure. The length of the poc_lsb_lt[i][j] syntax element is log2_max_pic_order_cnt_lsb_minus4+4 bits. The variable PocLsbLt[i][j] is derived as follows:

PocLsbLt[i][j]=ltrp_in_header_flag[i][RplsIdx[i]]?poc_lsb_It[i][j]:rpls_poc_lsb_It[listIdx][RplsIdx[i]][j]  (150)

delta_poc_msb_present_flag[i][j] equal to 1 specifies that delta_poc_msb_cycle_lt[i][j] is present. delta_poc_msb_present_flag[i][j] equal to 0 specifies that delta_poc_msb_cycle_lt[i][j] is not present. Let prevTid0Pic be the previous picture in decoding order that has nuh_layer_id the same as the slice or picture header referring to the ref_pic_lists( ) syntax structure, has TemporalId equal to 0, and is not a RASL or RADL picture. Let setOfPrevPocVals be a set consisting of the following:

-   -   the PicOrderCntVal of prevTid0Pic,     -   the PicOrderCntVal of each picture that is referred to by         entries in RefPicList[0] or RefPicList[1] of prevTid0Pic and has         nuh_layer_id the same as the current picture,     -   the PicOrderCntVal of each picture that follows prevTid0Pic in         decoding order, has nuh_layer_id the same as the current         picture, and precedes the current picture in decoding order.         When there is more than one value in setOfPrevPocVals for which         the value modulo MaxPicOrderCntLsb is equal to PocLsbLt[i][j],         the value of delta_poc_msb_present_flag[i][j] shall be equal to         1.         delta_poc_msb_cycle_lt[i][j] specifies the value of the variable         FullPocLt[i][j] as follows:

if( j = = 0 )  deltaPocMsbCycleLt[ i ][ j ] = delta_poc_msb_cycle_lt[ i ][j ] else (151)  deltaPocMsbCycleLt[ i ][ j ] = delta_poc_msb_cycle_lt[ i ][ j ] +  deltaPocMsbCycleLt[ i ][ j − 1 ] FullPocLt[ i ][ j ] = PicOrderCntVal − deltaPocMsbCycleLt[ i ][ j ] *   MaxPicOrderCntLsb − ( PicOrderCntVal & ( MaxPicOrderCntLsb −   1 ) ) + PocLsbLt[ i ][ j ] The value of delta_poc_msb_cycle_lt[i][j] shall be in the range of 0 to 2^((32−log2_max_pic_order_cnt_lsb_minus4−4)), inclusive. When not present, the value of delta_poc_msb_cycle_lt[i][j] is inferred to be equal to 0.

3.11. Reference Picture List Structure Syntax

In the latest WC draft text, the syntax structure ref_pic_lists( ) and semantics are as follows:

ref_pic_list_struct( listIdx, rplsIdx ) { Descriptor  num_ref_entries[ listIdx ][ rplsIdx ] ue (v)  if( long_term_ref_pics_flag )   ltrp_in_header_flag[ listIdx ][ rplsIdx ]  u (1)  for( i = 0, j = 0; i < num_ref_entries[ listIdx ][ rplsIdx ]; i++ ) {   if( inter_layer_ref_pics_present_flag )    inter_layer_ref_pic_flag[ listIdx ][ rplsIdx ][ i ]  u (1)   if( !inter_layer_ref_pic_flag[ listIdx ][ rplsIdx ][ i ] ) {    if( long_term_ref_pics_flag )     st_ref_pic_flag[ listIdx ][ rplsIdx ] [ i ]  u (1)    if( st_ref_pic_flag[ listIdx ][ rplsIdx ][ i ] ) {     abs_delta_poc_st[ listIdx ][ rplsIdx ][ i ] ue (v)     if( AbsDeltaPocSt[ listIdx ][ rplsIdx ][ i ] > 0 )      strp_entry_sign_flag[ listIdx ][ rplsIdx ] [ i ]  u (1)    } else if( !ltrp_inheader_flag[ listIdx ][ rplsIdx ] )     rpls_poc_isb_lt[ listIdx ][ rplsIdx ][ j ++ ]  u (v)   } else    ilrp_idx[ listIdx ] [ rplsIdx ][ i ] ue (v)  } } The ref_pic_list_struct(listIdx, rplsIdx) syntax structure may be present in an SPS, in a PH syntax structure, or in a slice header. Depending on whether the syntax structure is included in an SPS, a PH syntax structure, or a slice header, the following applies:

-   -   If present in a PH syntax structure or a slice header, the         ref_pic_list_struct(listIdx, rplsIdx) syntax structure specifies         reference picture list listIdx of the current picture (the         picture containing the slice).     -   Otherwise (present in an SPS), the ref_pic_list_struct(listIdx,         rplsIdx) syntax structure specifies a candidate for reference         picture list listIdx, and the term “the current picture” in the         semantics specified in the remainder of this clause refers to         each picture that 1) has a PH syntax structure containing         ph_rpl_idx[listIdx] equal to an index into the list of the         ref_pic_list_struct(listIdx, rplsIdx) syntax structures included         in the SPS or one or more slices containing         slice_rpl_idx[listIdx] equal to an index into the list of the         ref_pic_list_struct(listIdx, rplsIdx) syntax structures included         in the SPS, and 2) is in a CVS that refers to the SPS.         num_ref_entries[listIdx][rplsIdx] specifies the number of         entries in the ref_pic_list_struct(listIdx, rplsIdx) syntax         structure. The value of num_ref_entries[listIdx][rplsIdx] shall         be in the range of 0 to MaxDpbSize+13, inclusive, where         MaxDpbSize is as specified in clause A.4.2.         ltrp_in_header_flag[listIdx][rplsIdx] equal to 0 specifies that         the POC LSBs of the LTRP entries in the         ref_pic_list_struct(listIdx, rplsIdx) syntax structure are         present in the ref_pic_list_struct(listIdx, rplsIdx) syntax         structure. ltrp_in_header_flag[listIdx][rplsIdx] equal to 1         specifies that the POC LSBs of the LTRP entries in the         ref_pic_list_struct(listIdx, rplsIdx) syntax structure are not         present in the ref_pic_list_struct(listIdx, rplsIdx) syntax         structure.         inter_layer_ref_pic_flag[listIdx][rplsIdx][i] equal to 1         specifies that the i-th entry in the         ref_pic_list_struct(listIdx, rplsIdx) syntax structure is an         ILRP entry.         inter_layer_ref_pic_flag[listIdx][rplsIdx][i] equal to 0         specifies that the i-th entry in the         ref_pic_list_struct(listIdx, rplsIdx) syntax structure is not an         ILRP entry. When not present, the value of         inter_layer_ref_pic_flag[listIdx][rplsIdx][i] is inferred to be         equal to 0.         st_ref_pic_flag[listIdx][rplsIdx][i] equal to 1 specifies that         the i-th entry in the ref_pic_list_struct(listIdx, rplsIdx)         syntax structure is an STRP entry.         st_ref_pic_flag[listIdx][rplsIdx][i] equal to 0 specifies that         the i-th entry in the ref_pic_list_struct(listIdx, rplsIdx)         syntax structure is an LTRP entry. When         inter_layer_ref_pic_flag[listIdx][rplsIdx][i] is equal to 0 and         st_ref_pic_flag[listIdx][rplsIdx][i] is not present, the value         of st_ref_pic_flag[listIdx][rplsIdx][i] is inferred to be equal         to 1.         The variable NumLtrpEntries[listIdx][rplsIdx] is derived as         follows:

for( i = 0, NumLtrpEntries[ listIdx ][ rplsIdx ] = 0; i < num_ref_entries[ listIdx ][ rplsIdx ]; i++ )   if( !inter_layer_ref_pic_flag[ listIdx ][ rplsIdx ][ i ] &&   !st_ref_pic_flag[ listIdx ][ rplsIdx ][ i ] )  (152)    NumLtrpEntries[ listIdx ][ rplsIdx ]++ abs_delta_poc_st[listIdx][rplsIdx][i] specifies the value of the variable AbsDeltaPocSt[listIdx][rplsIdx][i] as follows:

if( ( sps_weighted_pred_flag | | sps_weighted_bipred_flag ) && i != 0 )  AbsDeltaPocSt[ listIdx ][ rplsIdx ][ i ] = abs_delta_poc_st[ (153)  listIdx ][ rplsIdx ][ i ] else  AbsDeltaPocSt[ listIdx ][ rplsIdx ][ i ] = abs_delta_poc_st[ listIdx ][  rplsIdx ][ i ] + 1 The value of abs_delta_poc_st[listIdx][rplsIdx][i] shall be in the range of 0 to 2¹⁵−1, inclusive. strp_entry_sign_flag[listIdx][rplsIdx][i] equal to 1 specifies that i-th entry in the syntax structure ref_pic_list_struct(listIdx, rplsIdx) has a value greater than or equal to 0. strp_entry_sign_flag[listIdx][rplsIdx][i] equal to 0 specifies that the i-th entry in the syntax structure ref_pic_list_struct(listIdx, rplsIdx) has a value less than 0. When not present, the value of strp_entry_sign_flag[listIdx if rplsIdx][i] is inferred to be equal to 1. The list DeltaPocValSt[listIdx][rplsIdx] is derived as follows:

for( i = 0; i < num_ref_entries[ listIdx ][ rplsIdx ]; i++ )  if( !inter_layer_ref_pic_flag[ listIdx ][ rplsIdx ][ i ] &&  st_ref_pic_flag[ listIdx ][ rplsIdx ] [ i ] ) (154)   DeltaPocValSt[ listIdx ][ rplsIdx ][ i ] = ( strp_entry_sign_flag[   listIdx ][ rplsIdx ][ i ] ) ?    AbsDeltaPocSt[ listIdx ][ rplsIdx ][ i ] : 0 − AbsDeltaPocSt[    listIdx ][ rplsIdx ][ i ] rpls_poc_lsb_lt[listIdx][rplsIdx][i] specifies the value of the picture order count modulo MaxPicOrderCntLsb of the picture referred to by the i-th entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure. The length of the rpls_poc_lsb_lt[listIdx][rplsIdx][i] syntax element is log2_max pic_order_cnt_lsb_minus4+4 bits. ilrp_idx[listIdx][rplsIdx][i] specifies the index, to the list of the direct reference layers, of the ILRP of the i-th entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure. The value of ilrp_idx[listIdx][rplsIdx][i] shall be in the range of 0 to NumDirectRefLayers[GeneralLayerIdx[nuh_layer_id]]−1, inclusive.

4. Examples of Technical Problems Solved by Disclosed Techniques

The existing designs for constraint flags have the following problems:

-   1) Currently, whenever there is a PTL syntax structure with     profileTierPresentFlag equal to 1, all the general constraint     flags/fields are signalled in that PTL syntax structure (SS).     Considering that PTL syntax structures may be included in DCI (one     or more times, each time with profileTierPresentFlag equal to 1), in     VPS (one or more times, the first time with profileTierPresentFlag     equal to 1, other times with profileTierPresentFlag equal to either     0 or 1), and in SPS (zero or one time, with profileTierPresentFlag     equal to 1), potentially there can be lots of redundant signalling     of the general constraint flags/fields. Furthermore, it is possible     that none of the general constraints may apply while in this case at     least one set of general constraint flags/fields is still signalled     for the bitstream of each OLS. -   2) In the latest VVC draft text, the general constraint flags are     used to constrain the values of some SPS/PH/SH syntax elements (SEs)     or their combinations via bitstream constraint in the semantics.     However, they can also be used to condition the presence of such     related SPS/PH/SH SEs, which would allow skipping the signalling of     bits for which their values are known thus avoiding waste of bits.     -   a. In the general_constraint_info( ) syntax in the latest VVC         draft text, the syntax elements such as no_aps_constraint_flag         affect a group of techniques such as ALF, CCALF, LMCS, scaling         list, and etc. However, the current design does not cover all         cases (e.g., in terms of specifying constraints on values of         related syntax elements or conditioning the presence of related         syntax elements). -   3) In the latest VVC draft text, some PPS SEs that relate to general     constraint flags can only have certain values depending on values of     certain general constraint flags. However, some semantics     constraints are missing to disallow illegal values of such PPS SEs. -   4) In the general_constraint_info( ) syntax in the latest VVC draft     text, a bunch of general constraint flags have interactions with     each other, i.e., certain values of general constraint flags depend     the values of other general constraint flags. However, there lacks     constraints to disallow illegal values of such general constraint     flags, by either bitstream constraints or syntax conditioning. -   5) Some syntax elements may be added to SPS and/or PPS to condition     the presences of some SPS/PPS/PH/SH syntax elements for saving bits. -   6) In the general_constraint_info( ) syntax in the latest VVC draft     text, constraint flags for a subset of coding tools and     functionalities are included. However, there are other coding tools     (e.g., WPP, entropy coding sync, weighted prediction, weighted     bi-prediction, SMVD, MMVD, ISP, MRL, MIP, LFNST, Palette, ACT,     scaling list, and etc.) and functionalities (e.g., single layer     only, one sub-picture only, no inter-layer prediction, no virtual     boundaries, no long term reference, no 32×32 max luma transform     size, no MER, and etc.) that don't have corresponding constraint     flags. -   7) In the latest VVC draft text, APSs do not refer to an PPS, an     SPS, or an VPS. However, the semantics of some APS SEs depends on     values of SEs of VPS, SPS, or PPS. Either all such dependencies     should be removed or an PPS or SPS or VPS ID is added to the APS     syntax to allow the referencing of PPS or SPS or VPS thus allowing     such semantics dependencies. -   8) Once the associated information of a feature can be signalled     either in the PH or SH, there might be a flag (named     X_info_in_ph_flag) signalled in the PPS to specify whether they are     going to be signalled in the PH or SH. Right now in the VVC spec,     the flag X_info_in_ph_flag is always signalled in the PPS, without     any condition. However, if there is only one slice in the picture,     there is no need to signal this X_info_in_ph_flag in the PPS. It is     proposed to conditional signal the PPS flag X_info_in_ph_flag (any     existing features or potential features in the future) based on the     already known picture partition flag in the bitstream (e.g.,     no_pic_partition_flag in the PPS). -   9) Currently, the values of some APS syntax elements are constrained     based on ChromaArrayType derived from SPS syntax elements     chroma_format_idc and separate_colour_plane_flag. However, this     would cause semantics dependency since there is no PPS/SPS ID in the     APS syntax structure. Therefore, this sementics dependency of APS on     SPS should not occur. -   10) Currently, the GCI syntax structure would be signaled as long as     the profileTierPresentFlag associated with profile_tier_level( )     syntax structure is equal to 1. In such case, multiple GCI syntax     structures with different content may be signalled for a same     profile ID, which may be confused and not efficient. a. Moreover,     the reserved GCI syntax elements are counted by bytes, which may be     not desirable. -   11) Currently, the GCI fields/SEs are used to constrain other SEs,     but not all cases are fully considered, which may cause     unintentional problems for the codec design. For example, below     problems exists in the current draft text.     -   a. The RPL related SEs and some GCI SEs are not constrained by         the value of intra_only_constraint_flag.     -   b. The SEs in the SPS/PPS/PH/SH are not completely constrained         by the GCI SEs, e.g., the partition/tile/slice related SEs in         the SPS/PPS/PH/SH are not constrained by the value of         one_tile_per_pic_constraint_flag, and/or         one_slice_per_pic_constraint_flag.     -   c. sps_ccalf_enabled_flag, ph_num_alf_aps_ids_luma,         slice_num_alf_aps_ids_luma, ph_alf_cb_flag, ph_alf_cr_flag,         sh_alf_cb_flag, and sh_alf_cr_flag should be constrained by the         value of no_aps_constraint_flag.     -   d. Some GCI SEs may need to be constrained by other GCI SEs,         e.g., the inter layer SEs are not constrained by the value of         all_layers_independent_constraint_flag, and         no_bdpcm_constraint_flag is not constrained by the value of no         transform_skip_constraint_flag.     -   e. The definition of intra_only_constraint_flag may need to         consider the nuh_layer_type for each coded slice NAL unit. -   12) Currently, an aps_chroma_present_flag is signalled in the APS     syntax structure and used to condition the signalling of the chroma     scaling list SEs in the scaling_list_data( ) syntax structure. The     aps_chroma_present_flag is required to be equal to 1 for non-4:0:0     and non-separate-color-plane (e.g., chromaArrayType equal to 1)     coding. However, the aps_chroma_present_flag could also be equal to     0 for chromaArrayType equal to 1 coding.     -   a. Moreover, currently the scaling list APS ID is signaled for         both luma and chroma, which may be not efficient.

5. Example Embodiments and Techniques

To solve the above problems and some other problems not mentioned, methods as summarized below are disclosed. The inventions should be considered as examples to explain the general concepts and should not be interpreted in a narrow way. Furthermore, these inventions can be applied individually or combined in any manner.

-   1. Regarding the signalling of general constraint flags/fields in     general for solving the first problem, one or more of the following     approaches are disclosed:     -   1) A presence flag may be added to the PTL syntax structure to         specify whether the general_constraint_info( ) syntax structure         is present in the PTL syntax structure.         -   a. In one example, when no general_constraint_info( ) syntax             structure is present for an OLS, a default value is inferred             for each of the general constraint flags/fields.             -   i. In one example, when no general_constraint_info( )                 syntax structure is present for an OLS, each of the                 general constraint flags/fields is inferred to be a                 value that specifies that no particular constraint is                 imposed for the bitstream of the OLS. For example, the                 values of intra_only_constraint_flag,                 no_res_change_in_clvs_constraint_flag, and                 one_tile_per_pic_constraint_flag are all inferred to be                 equal to 0.         -   b. In one example, in the DCI, when there is more than one             PTL syntax structure in it, it may be required that at most             one of those PTL syntax structures contains a             general_constraint_info( ) syntax structure, and when             present, that general_constraint_info( ) syntax structure             applies to the entire bitstream.             -   i. Furthermore, it may be required that only the first                 PTL syntax structure in the DCI may contain a                 general_constraint_info( ) syntax structure, and the                 general constraints information associated with the                 first DCI PTL syntax structure in the DCI (explicitly                 signalled or inferred) is considered as the general                 constraints information associated with the DCI, which                 applies to the entire bitstream.         -   c. In one example, when a DCI is present in the bitstream,             it may be required that no PTL syntax structure present in a             VPS or SPS shall contain a general_constraint_info( ) syntax             structure, and the general constraints information             associated with the DCI (explicitly signalled or inferred)             applies to each OLS in each CVS in the bitstream.             -   i. Alternatively, when a DCI is present in the                 bitstream, it may be required that no PTL syntax                 structure present in a VPS shall contain a                 general_constraint_info( ) syntax structure, and the                 general constraints information associated with the DCI                 (explicitly signalled or inferred) applies to each OLS                 containing more than one layer in each CVS in the                 bitstream.         -   d. In one example, in a VPS, when there is more than one PTL             syntax structure in it, it may be required that only one of             those PTL syntax structures may contain a             general_constraint_info( ) syntax structure, and that             general_constraint_info( ) syntax structure applies to each             OLS of each CVS in the bitstream.             -   i. Alternatively, in a VPS, when there is more than one                 PTL syntax structure in it, it may be required that only                 the first PTL syntax structure in the VPS may contain a                 general_constraint_info( ) syntax structure, and the                 general constraints information associated with the                 first PTL syntax structure (explicitly signalled or                 inferred) applies to each OLS of each CVS in the                 bitstream.         -   e. In one example, when there is more than one PTL (and/or             general_constraint_info( )) syntax structure signaled in DCI             and/or SPS and/or VPS, those PTL (and/or             general_constraint_info( )) syntax structures must have the             same content in a conformance bitstream.             -   i. In one example, when there is more than one PTL                 (and/or general_constraint_info( )) syntax structure                 signaled for an OLS, those PTL (and/or                 general_constraint_info( )) syntax structures must have                 the same content in a conformance bitstream.             -   ii. In one example, when there is more than one PTL                 (and/or general_constraint_info( )) syntax structure                 signaled for a CVS, those PTL (and/or                 general_constraint_info( )) syntax structures must have                 the same content in a conformance bitstream.         -   f. In one example, at most one PTL (and/or             general_constraint_info( )) syntax structure is allowed to             be signaled in DCI and/or SPS and/or VPS in a conformance             bitstream.             -   i. In one example, at most one PTL (and/or                 general_constraint_info( )) syntax structure is allowed                 to be signaled for an OLS in a conformance bitstream.             -   ii. In one example, at most one PTL (and/or                 general_constraint_info( )) syntax structure is allowed                 to be signaled for a CVS in a conformance bitstream.         -   g. In one example, when there are multiple PTL syntax             structures signaled in DCI targeting for multiple OLSs, a             syntax element may be added to the DCI syntax structure to             specify the index, to the list of PLT syntax structures in             the DCI, of the PTL syntax structure that applies to the             i-th OLS.             -   i. Additionally, if there is only one OLS in a                 bitstream, the signaling of the above-mentioned syntax                 element may be skipped and/or the value of the syntax                 element is inferred to a certain value (such as 0).         -   h. In one example, when there are multiple             general_constraint_info( )) syntax structures in DCI and/or             SPS and/or VPS, and the values for a particular general             constraint flag/field are different for an OLS, then as long             as anyone of the general constraint flags imposes a             particular constraint, the particular constraint would be             applied to this OLS.             -   i. In one example, when any of the general constraint                 flags in VPS/SPS specify that a particular constraint is                 imposed for an OLS, whereas the corresponding general                 constraint flag in DCI specifies that a particular                 constraint is not imposed for an OLS, then that OLS may                 conform to the tighter constraint (e.g., impose such                 particular constraint to that OLS as indicated in                 VPS/SPS).                 -   1. Alternatively, when any of the general constraint                     flags in VPS/SPS specify that a particular                     constraint is not imposed for an OLS, whereas the                     corresponding general constraint flag in DCI                     specifies that a particular constraint is imposed                     for an OLS, then that OLS may conform to the tighter                     constraint (e.g., impose such particular constraint                     to that OLS as indicated in DCI).             -   ii. In one example, for any particular aspect associated                 with a general constraint syntax element that impose a                 constraint to an OLS, the corresponding general                 constraint syntax element carried in DCI has to have a                 value that indicates a more relaxed than but cannot be                 tighter than the value of the same constraint regarding                 that aspect indicated in VPS/SPS.                 -   1. In one example, if any of the general constraint                     flags/fields in VPS/SPS specify that a particular                     constraint is not imposed for an OLS, then a                     bitstream conformance may be added to require that                     the value of the corresponding general constraint                     flag in DCI is equal to 0 for that OLS (in this                     case, the value of the corresponding general                     constraint flag in DCI cannot be equal to 1).                 -   2. In one example, if any of the general constraint                     flags/fields in VPS/SPS specify that a particular                     constraint is imposed for an OLS, then the value of                     the corresponding general constraint flag in DCI may                     be equal to 0 or 1 for that OLS.             -   iii. Alternatively, oppositely, for any particular                 aspect associated with a general constraint syntax                 element that impose a constraint to an OLS, the                 corresponding general constraint syntax element carried                 in DCI has to have a value that indicates a tighter than                 but cannot be more relaxed than the value of the same                 constraint regarding that aspect indicated in VPS/SPS.                 -   1. In one example, if any of the general constraint                     flags/fields in VPS/SPS specify that a particular                     constraint is imposed for an OLS, then a bitstream                     conformance may be added to require that the value                     of the corresponding general constraint flag in DCI                     is equal to 1 for that OLS (in this case, the value                     of the corresponding general constraint flag in DCI                     cannot be equal to 0).                 -   2. In one example, if any of the general constraint                     flags/fields in VPS/SPS specify that a particular                     constraint is not imposed for an OLS, then the value                     of the corresponding general constraint flag in DCI                     may be equal to 0 or 1 for that OLS.         -   i. In one example, multiple sets of different default values             for the general constraint flags/fields may be pre-defined.             -   i. Alternatively, furthermore, an indication of one set                 among the multiple sets may be signalled in a                 DCI/VPS/SPS.             -   ii. Alternatively, only one set is pre-defined.                 -   1. Alternatively, furthermore, one flag may be                     present in DCI/VPS/SPS to specify whether the one                     set is used. iii. In one example, for one of the                     multiple sets, each of the general constraint                     flags/fields is inferred to be a value that                     specifies that a particular constraint is not                     imposed for the bitstream of the OLS. For example,                     the values of intra_only_constraint_flag,                     no_res_change_in_clvs_constraint_flag, and                     one_tile_per_pic_constraint_flag are all inferred to                     be equal to 0.             -   iv. In one example, for one or some of the multiple                 sets, the value of max_bitdepth_constraint_idc may be                 inferred to be equal to a particular value, e.g., 2. -   2. Regarding the signalling of SPS/PH/SH syntax elements based on     the general constraint flags for solving the second problem:     -   1) Depending on the values of general constraint flags, the         signaling of the corresponding syntax elements in SPS/PH/SH may         be skipped, e.g., as in the first embodiment.         -   a. In one example, signalling of some SPS syntax elements             may be skipped according to some general constraint flags.             -   i. For example, in case of the value of the general                 constraint field max_chroma_format_constraint_idc is                 equal to 0, the signalling of the corresponding SPS                 syntax element chroma_format_idc may be skipped.                 -   a) Additionally, furthermore, when                     max_chroma_format_constraint_idc is equal to 0, the                     value of chroma_format_idc is inferred to be equal                     to 0.             -   ii. For example, in case of the value of the general                 constraint field max_bitdepth_constraint_idc is equal to                 0, the signalling of the corresponding SPS syntax                 element bit_depth_minus8 may be skipped.                 -   a) Additionally, furthermore, when                     max_bitdepth_constraint_idc is equal to 0, the value                     of bit_depth_minus8 is inferred to be equal to 0.             -   iii. For example, in case of the value of the general                 constraint flag no_aps_constraint_flag is equal to 1,                 the signalling of the APS-related SPS syntax elements                 (such as sps_lmcs_enabled_flag,                 sps_scaling_list_enabled_flag, sps_alf_enabled_flag,                 sps_ccalf_enabled_flag, and etc) may be skipped.                 -   a) Additionally, when no_aps_constraint_flag is                     equal to 1, the value of the above-mentioned each of                     the APS-related SPS syntax elements is inferred to                     be equal to 0.                 -   b) Alternatively, furthermore, in case of the value                     of the general constraint flag                     no_aps_constraint_flag is equal to 1, the NAL unit                     type is disallowed to be equal to PREFIX_APS_NUT or                     SUFFIX_APS_NUT.             -   iv. For example, in case of the value of the general                 constraint flag intra_only_constraint_flag is equal to                 1, the signalling of the one or more of inter-related                 SPS syntax elements (such as sps_weighted_pred_flag,                 sps_weighted_bipred_flag, long_term_ref_pics_flag,                 sps_idr_rpl_present_flag, rpl1_same_as_rpl0_flag,                 gdr_enabled_flag, res_change_in_clvs_allowed_flag,                 sps_ref_wraparound_enabled_flag,                 sps_temporal_mvp_enabled_flag, sps_sbtmvp_enabled_flag,                 sps_amvr_enabled_flag, sps_bdof_enabled_flag,                 sps_dmvr_enabled_flag, sps_sbt_enabled_flag,                 sps_affine_enabled_flag, sps_bcw_enabled_flag,                 sps_ciip_enabled_flag, sps_fpel_mmvd_enabled_flag,                 sps_gpm_enabled_flag, and etc) may be skipped.                 -   a) Additionally, when intra_only_constraint_flag is                     equal to 1, the value of each of the above-mentioned                     the inter-related SPS syntax elements is inferred to                     be equal to 0.             -   v. For example, the signalling of the corresponding SPS                 syntax element Y1 may be skipped in case of the value of                 the general constraint flag Y2 is equal to 1.                 -   a) Additionally, when not present (in the case of                     the general constraint flag Y2 is equal to 1), the                     value of the corresponding SPS syntax element Y1 is                     inferred to be equal to 0.                 -   b) For example, Y1 is sps_ladf_enabled_flag, and Y2                     is no_ladf_constraint_flag.                 -   c) For example, Y1 is gdr_enabled_flag, and Y2 is                     no_gdr_constraint_flag.                 -   d) For example, Y1 is                     res_change_in_clvs_allowed_flag, and Y2 is                     no_res_change_in_clvs_constraint_flag.                 -   e) For example, Y1 is gtbtt_dual_tree_intra_flag,                     and Y2 is no_gtbtt_dual_tree_intra_constraint_flag.                 -   f) For example, Y1 is                     partition_constraints_override_enabled_flag, and Y2                     is                     no_partition_constraints_override_constraint_flag.                 -   g) For example, Y1 is sps_joint_cbcr_enabled_flag,                     and Y2 is no_joint_cbcr_constraint_flag.                 -   h) For example, Y1 is sps_sao_enabled_flag, and Y2                     is no_sao_constraint_flag.                 -   i) For example, Y1 is sps_alf_enabled_flag, and Y2                     is no_alf_constraint_flag.                 -   j) For example, Y1=sps_ccalf_enabled_flag,                     Y2=no_ccalf_constraint_flag.                 -   k) For example, Y1 is                     sps_transform_skip_enabled_flag, and Y2 is                     no_transform_skip_constraint_flag.                 -   l) For example, Y1 is sps_bdpcm_enabled_flag, and Y2                     is no_bdpcm_constraint_flag.                 -   m) For example, Y1 is                     sps_ref_wraparound_enabled_flag, and Y2 is                     no_ref_wraparound_constraint_flag.                 -   n) For example, Y1=sps_temporal_mvp_enabled_flag,                     Y2=no_temporal_mvp_constraint_flag                 -   o) For example, Y1 is sps_sbtmvp_enabled_flag, and                     Y2 is no_sbtmvp_constraint_flag.                 -   p) For example, Y1 is sps_amvr_enabled_flag, and Y2                     is no_amvr_constraint_flag.                 -   q) For example, Y1 is sps_bdof_enabled_flag, and Y2                     is no_bdof_constraint_flag.                 -   r) For example, Y1 is sps_dmvr_enabled_flag, and Y2                     is no_dmvr_constraint_flag.                 -   s) For example, Y1 is sps_cclm_enabled_flag, and Y2                     is no_cclm_constraint_flag.                 -   t) For example, Y1 is sps_mts_enabled_flag, and Y2                     is no_mts_constraint_flag.                 -   u) For example, Y1 is sps_sbt_enabled_flag, and Y2                     is no_sbt_constraint_flag.                 -   v) For example, Y1 is sps_affine_enabled_flag, and                     Y2 is no_affine_motion_constraint_flag.                 -   w) For example, Y1 is sps_bcw_enabled_flag, and Y2                     is no_bcw_constraint_flag.                 -   x) For example, Y1 is sps_ibc_enabled_flag, and Y2                     is no_ibc_constraint_flag.                 -   y) For example, Y1 is sps_ciip_enabled_flag, and Y2                     is no_ciip_constraint_flag.                 -   z) For example, Y1 is sps_fpel_mmvd_enabled_flag,                     and Y2 is no_fpel_mmvd_constraint_flag.                 -   aa) For example, Y1 is sps_dep_quant_enabled_flag,                     and Y2 is no_dep_quant_constraint_flag.                 -   bb) For example, Y1 is                     sps_sign_data_hiding_enabled_flag, and Y2 is                     no_sign_data_hiding_constraint_flag.                 -   cc) For example, Y1 is sps_gpm_enabled_flag, and Y2                     is no_gpm_constraint_flag.             -   vi. Alternatively, a bitstream constraint may be added                 to require that the value of the related syntax element                 in SPS be equal to a certain value based on the value of                 the corresponding general constraint flag.                 -   a) In one example (in this case the above mentioned                     SPS syntax element Y1 is signalled or inferred), a                     bitstream constraint may be added that when the                     general constraint flag Y2 is equal to 1, the value                     of the corresponding SPS syntax element Y1 is                     required to be equal to 0.                 -   b) In one example (in this case the APS-related SPS                     syntax element is signalled or inferred), a                     bitstream constraint may be added that when                     no_aps_constraint_flag is equal to 1, the value of                     each of the APS-related SPS syntax elements (such as                     sps_lmcs_enabled_flag,                     sps_scaling_list_enabled_flag, sps_alf_enabled_flag,                     sps_ccalf_enabled_flag, and etc) is required to be                     equal to 0.                 -   c) In one example (in this case the inter-related                     SPS syntax element is signalled or inferred), a                     bitstream constraint may be added that when                     intra_only_constraint_flag is equal to 1, the value                     of each of the above inter-related SPS syntax                     elements (such as sps_weighted_pred_flag,                     sps_weighted_bipred_flag, long_term_ref_pics_flag,                     sps_idr_rpl_present_flag, rpl1_same_as_rpl0_flag,                     gdr_enabled_flag, res_change_in_clvs_allowed_flag,                     sps_ref_wraparound_enabled_flag,                     sps_temporal_mvp_enabled_flag,                     sps_sbtmvp_enabled_flag, sps_amvr_enabled_flag,                     sps_bdof_enabled_flag, sps_dmvr_enabled_flag,                     sps_sbt_enabled_flag, sps_affine_enabled_flag,                     sps_bcw_enabled_flag, sps_ciip_enabled_flag,                     sps_fpel_mmvd_enabled_flag, sps_gpm_enabled_flag,                     and etc) is required to be equal to 0.         -   b. In one example, signalling of one or multiple PH syntax             elements may be skipped according to the values of some             general constraint flags.             -   i. For example, when intra_only_constraint_flag is equal                 to 1, the signalling of the inter-related PH syntax                 elements such as ph_inter_slice_allowed_flag may be                 skipped.                 -   a) Additionally, when intra_only_constraint_flag is                     equal to 1, the value of each of the inter-related                     PH syntax elements such as                     ph_inter_slice_allowed_flag is inferred to be equal                     to 0.             -   ii. For example, when intra_only_constraint_flag is                 equal to 1, the signalling of the PH syntax elements in                 the syntax structure ref_pic_lists( ) and the syntax                 structure ref_pic_list_struct(listIdx, rplsIdx) included                 in the PH may be skipped.                 -   a) For example, when intra_only_constraint_flag is                     equal to 1, the syntax elements such as                     rpl_sps_flag[ ], rpl_idx[ ], poc_isb_lt[ ][ ],                     delta_poc_msb_present_flag[ ][ ],                     delta_poc_msb_cycle_lt[ ][ ] in the syntax structure                     ref_pic_lists( ) that included in the PH may be                     skipped.                 -   b) For example, when intra_only_constraint_flag is                     equal to 1, the syntax elements such as                     num_ref_entries[ ][ ], ltrp_in_header_flag[ ][ ],                     inter_layer_ref_pic_flag[ ][ ][ ], st_ref_pic_flag[                     ][ ][ ], abs_delta_poc_st[ ][ ][ ],                     strp_entry_sign_flag[ ][ ][ ], rpls_poc_lsb_lt[ ][                     ][ ], ilrp_idx[ ][ ][ ] in the syntax structure                     ref_pic_list_struct(listIdx, rplsIdx) that included                     in the PH may be skipped.             -   iii. Alternatively (in this case the corresponding                 syntax elements in PH are not conditionally signalled or                 skipped depending on the values of related general                 constraint flags/fields), in one example, a bitstream                 constraint may be added to require that the value of the                 related syntax element in PH be equal to a certain value                 based on the value of the corresponding general                 constraint flag.                 -   a) In one example (in this case the PH syntax                     element ph_inter_slice_allowed_flag is signalled or                     inferred), when intra_only_constraint_flag is equal                     to 1, a bitstream constraint may be added such that                     the value of each of the inter-related PH syntax                     elements such as ph_inter_slice_allowed_flag is                     required to be equal to 0.                 -   b) In one example (in this case the syntax elements                     in ref_pic_lists( ) and ref_pic_list_struct(listIdx,                     rplsIdx) included in the PH are signalled or                     inferred), a bitstream constraint may be added that                     the syntax elements in reference picture lists                     included in PH are required to be never used.         -   c. In one example, signalling of one or multiple SH syntax             elements may be skipped according to the values of some             general constraint flags.             -   i. For example, the signalling of the RPL-related SH                 syntax element num_ref_idx_active_override_flag may be                 skipped, in case of the value of                 intra_only_constraint_flag is equal to 1.                 -   a) Additionally, when intra_only_constraint_flag is                     equal to 1, the value of                     num_ref_idx_active_override_flag is inferred to be                     equal to 0.             -   ii. For example, in case of intra_only_constraint_flag                 is equal to 1, the signalling of the RPL-related syntax                 elements in the syntax structure ref_pic_lists( ) and                 the syntax structure ref_pic_list_struct(listIdx,                 rplsIdx) included in the SH may be skipped.                 -   a) For example, when intra_only_constraint_flag is                     equal to 1, the syntax elements such as                     rpl_sps_flag[ ], rpl_idx[ ], poc_lsb_lt[ ][ ],                     delta_poc_msb_present_flag[ ][ ],                     delta_poc_msb_cycle_lt[ ][ ] in the syntax structure                     ref_pic_lists( ) that included in the SH may be                     skipped.                 -   b) For example, when intra_only_constraint_flag is                     equal to 1, the syntax elements such as                     num_ref_entries[ ][ ], ltrp_in_header_flag[ ][ ],                     inter_layer_ref_pic_flag[ ][ ][ ], st_ref_pic_flag[                     ][ ][ ], abs_delta_poc_st[ ][ ][ ],                     strp_entry_sign_flag[ ][ ][ ], rpls_poc_lsb_lt[ ][                     ][ ], ilrp_idx[ ][ ][ ] in the syntax structure                     ref_pic_list_struct(listIdx, rplsIdx) that included                     in the SH may be skipped.             -   iii. Alternatively (in this case the corresponding                 syntax elements in SH are not conditionally signalled or                 skipped depending on the values of related general                 constraint flags/fields), in one example, a bitstream                 constraint may be added to require that the value of                 each of the related syntax elements in SH is be equal to                 a certain value according to the value of the                 corresponding general constraint flag.                 -   a) In one example (in this case the SH syntax                     element num_ref_idx_active_override_flag is                     signalled or inferred), when                     intra_only_constraint_flag is equal to 1, a                     bitstream constraint may be added such that the                     syntax element num_ref_idx_active_override_flag in                     SH is required to be equal to 0.                 -   b) In one example (in this case the SH syntax                     elements in ref_pic_lists( ) and                     ref_pic_list_struct(listIdx, rplsIdx) included in                     the SH are signalled or inferred), when                     intra_only_constraint_flag is equal to 1, a                     bitstream constraint may be added such that the                     syntax elements in reference picture lists included                     in SH are required to be never used.         -   d. In above examples, the general constraint flags/fields             used to determine whether signalling of one or multiple SH             syntax elements is skipped may be replaced by a new syntax             element in SPS/PPS/PH/SH.         -   e. In above examples, the general constraint flags/fields             used to determine whether signalling of one or multiple PH             syntax elements is skipped may be replaced by a new syntax             element in SPS/PPS/PH.         -   f. In above examples, the general constraint flags/fields             used to determine whether signalling of one or multiple SPS             syntax elements is skipped may be replaced by a new syntax             element in SPS. -   3. Regarding the constraints of PPS syntax elements based on the     general constraint flags for solving the third problem:     -   1) Depending on the values of general constraint flags, the         values of the corresponding syntax elements in PPS may be         constrained, e.g., as in the second embodiment.         -   a. In one example, depending on the values of general             constraint flags, bitstream constraints may be added such             that the value of a syntax element in PPS is required to be             equal to a certain value.             -   i. For example, when one the per_pic_constraint_flag is                 equal to 1, the values of num_exp_tile_columns_minus1,                 and/or num_exp_tile_rows_minus1, and/or rect_slice_flag                 are required to be equal to 0.             -   ii. For example, when one_slice_per_pic_constraint_flag                 is equal to 1, the value of rect_slice_flag is required                 to be equal to 1.             -   iii. For example, when both                 one_tile_per_pic_constraint_flag and                 one_slice_per_pic_constraint_flag are equal to 1, the                 value of no_pic_partition_flag is required to be equal                 to 1.             -   iv. For example, when intra_only_constraint_flag is                 equal to 1, the values of rpl1_idx_present_flag and                 num_ref_idx_default_active_minus1[ ] are required to be                 equal to 0. -   4. Regarding the constraints on general constraint flags to disallow     illegal values of such general constraint flags for solving the     fourth problem:     -   1) In the syntax general_constraint_info( ), the value of one         general constraint flag may be dependent on the value of another         general constraint flag, e.g., as in the third embodiment.         -   a. In one example, depending on the values of earlier             signalled general constraint flags, the signaling of some             general constraint flags in the syntax             general_constraint_info( ) may be skipped.             -   i. In one example, in case of the value of                 one_slice_per_pic_constraint_flag is equal to 1, the                 signalling of the syntax element                 one_subpic_per_pic_constraint_flag in the syntax                 general_constraint_info( ) may be skipped.                 -   1. Additionally, when                     one_slice_per_pic_constraint_flag is equal to 1, the                     value of one_subpic_per_pic_constraint_flag is                     inferred to be equal to 1.             -   ii. In one example, in case of the value of                 no_transform_skip_constraint_flag is equal to 1, the                 signalling of the syntax element                 no_bdpcm_constraint_flag in the syntax                 general_constraint_info( ) may be skipped.                 -   1. Additionally, when                     no_transform_skip_constraint_flag is equal to 1, the                     value of no_bdpcm_constraint_flag is inferred to be                     equal to 1.             -   iii. For example, in case of the value of                 intra_only_constraint_flag is equal to 1, the signalling                 of the inter-related syntax elements (such as                 no_res_change_in_clvs_constraint_flag,                 no_ref_wraparound_constraint_flag,                 no_temporal_mvp_constraint_flag,                 no_sbtmvp_constraint_flag, no_amvr_constraint_flag,                 no_bdof_constraint_flag, no_dmvr_constraint_flag,                 no_sbt_constraint_flag,                 no_affine_motion_constraint_flag,                 no_bcw_constraint_flag, no_ciip_constraint_flag,                 no_fpel_mmvd_constraint_flag, no_gpm_constraint_flag) in                 the general_constraint_info( ) syntax structure may be                 skipped.                 -   2. Additionally, when intra_only_constraint_flag is                     equal to 1, the value of each of the above-mentioned                     inter-related syntax elements in the                     general_constraint_info( ) syntax structure is                     inferred to be equal to 1.         -   b. In one example, alternatively (in this case the general             constraint flags are not conditionally signalled or skipped             depending on values of earlier general constraint flags),             bitstream constraints may be added such that the value of             one general constraint flag is required to be equal to a             certain value according to the value of the related earlier             general constraint flag(s).             -   i. In one example, when intra_only_constraint_flag is                 equal to 1, the value of each of the inter-related                 general constraint flags as mentioned in the above                 bullet is required to be equal to 1.             -   ii. In one example, when intra_only_constraint_flag is                 equal to 1, at least one of the values of                 no_idr_constraint_flag and no_cra_constraint_flag is                 required to be equal to 0.             -   iii. In one example, when                 no_transform_skip_constraint_flag equal to 1, the value                 of no_bdpcm_constraint_flag is required to be equal to                 1.             -   iv. In one example, when no_aps_constraint_flag is equal                 to 1, the value of no_alf_constraint_flag is required to                 be equal to 1.         -   c. In one example, additionally, bitstream constraints may             be added to require the values of some general constraint             flags be equal to certain values, and, if necessary, under             certain conditions.             -   i. In one example, a bitstream constraint may be added                 to constrain the values of the combination of multiple                 general constraint flags, e.g., at least one of the                 values of no_gdr_constraint_flag,                 no_idr_constraint_flag, and no_cra_constraint_flag is                 required to be equal to 0.             -   ii. In one example, a bitstream constraint may be added                 to constrain the range of general constraint fields.                 -   1. For example, max_bitdepth_constraint_idc is                     required to be in the range of 0 to X (such as X=8),                     inclusive.                 -   2. For example, when general_profile_idc is equal to                     A (such as A=1), max_bitdepth_constraint_idc is                     required to be in the range of 0 to B (such as B=2),                     inclusive. -   5. Regarding adding new SPS/PPS syntax elements for solving the     fifth problem:     -   1) New SPS and/or PPS syntax elements may be added to condition         the related syntax elements in SPS/PPS/PH/SH, e.g., as in the         fourth embodiment.         -   a. In one example, a new SPS syntax element (e.g.,             sps_intra_only_flag) and/or a new PPS syntax element (e.g.,             pps_intra_only_flag) may be added to condition the inter             prediction related syntax elements in SPS/PPS/PH/SH.             -   i. In one example, when the general constraint flag                 intra_only_constraint_flag is equal to 1, the signaling                 of the new SPS syntax element sps_intra_only_flag and/or                 the new PPS syntax element pps_intra_only_flag may be                 skipped.                 -   1. Additionally, when intra_only_constraint_flag is                     equal to 1, the value of the new SPS syntax element                     sps_intra_only_flag is inferred to be equal to 1,                     and/or, the value of the new PPS syntax element                     pps_intra_only_flag is inferred to be equal to 1.             -   ii. In one example, in case of the value of the new SPS                 syntax element (e.g., sps_intra_only_flag) is equal to                 1, the signalling of the inter-related SPS syntax                 elements (such as sps_weighted_pred_flag,                 sps_weighted_bipred_flag, long_term_ref_pics_flag,                 sps_idr_rpl_present_flag, rpl1_same_as_rpl0_flag,                 gdr_enabled_flag, res_change_in_clvs_allowed_flag,                 sps_ref_wraparound_enabled_flag,                 sps_temporal_mvp_enabled_flag, sps_sbtmvp_enabled_flag,                 sps_amvr_enabled_flag, sps_bdof_enabled_flag,                 sps_dmvr_enabled_flag, sps_sbt_enabled_flag,                 sps_affine_enabled_flag, sps_bcw_enabled_flag,                 sps_ciip_enabled_flag, sps_fpel_mmvd_enabled_flag,                 sps_gpm_enabled_flag, and etc) may be skipped.                 -   2. Additionally, when the new SPS syntax element                     sps_intra_only_flag is equal to 1, the value of each                     of the inter related SPS syntax elements is inferred                     to be equal to a certain value (such as 0 or 1).             -   iii. In one example, in case of the value of the new                 SPS/PPS syntax element (e.g., sps_intra_only_flag,                 and/or pps_intra_only_flag) is equal to 1, the                 signalling of the corresponding inter-related and                 RPL-related syntax elements included in PH and/or SH may                 be skipped.                 -   1. In one example, the above-mentioned inter-related                     PH syntax element may be                     ph_inter_slice_allowed_flag.                 -   2. In one example, the above-mentioned RPL-related                     SH syntax element may be                     num_ref_idx_active_override_flag.                 -   3. In one example, the above-mentioned corresponding                     RPL-related syntax element may be the syntax                     elements in the syntax structure ref_pic_lists( )                     and the syntax structure                     ref_pic_list_struct(listIdx, rplsIdx) included in                     the PH and/or SH.                 -   4. Additionally, when the new syntax element                     sps_intra_only_flag, and/or pps_intra_only_flag is                     equal to 1, the value of each of the corresponding                     inter-related and RPL-related syntax elements in PH                     and/or SH is inferred to be equal a certain value                     (such as 0 or 1).             -   iv. In one example, in case of the value of the new PPS                 syntax element (e.g., pps_intra_only_flag) is equal to                 1, the signalling of the corresponding PPS syntax                 elements may be skipped.                 -   1. For example, the above-mentioned corresponding                     PPS syntax element may be rpl1_idx_present_flag.                 -   2. For example, the above-mentioned corresponding                     PPS syntax element may be                     num_ref_idx_default_active_minus1[ ].                 -   3. Additionally, when the new PPS syntax element                     pps_intra_only_flag is equal to 1, the value of the                     corresponding PPS syntax elements is inferred to be                     equal to a certain value (such as 0 or 1).             -   v. Alternatively (in this case the new SPS and/or PPS                 syntax elements sps_intra_only_flag and/or                 pps_intra_only_flag is conditionally signalled or                 skipped depending on the values of                 intra_only_constraint_flag), in one example, when                 intra_only_constraint_flag is equal to 1, bitstream                 constraints may be added to require the value of the new                 SPS and/or PPS syntax elements sps_intra_only_flag                 and/or pps_intra_only_flag to be equal to 1.             -   vi. Alternatively (in this case the SPS/PPS/PH/SH syntax                 elements related to the new SPS/PPS syntax elements are                 not conditionally signalled or skipped depending on the                 values of the new SPS/PPS syntax elements), in one                 example, according to the values of the new SPS/PPS                 syntax elements, bitstream constraints may be added that                 the value of each of the related syntax elements in                 SPS/PPS/PH/SH is required to be equal to a certain value                 (such as 0 or 1).                 -   1. In one example (in this case the new PPS syntax                     element pps_intra_only_flag is signalled or                     inferred), additionally, when the new SPS syntax                     element sps_intra_only_flag is equal to 1, a                     bitstream constraint may be added such that the                     value of the new PPS syntax element                     pps_intra_only_flag is required to be equal to 1.                 -   2. In one example (in this case the SPS syntax                     elements related to the new SPS syntax elements are                     signalled or inferred), a bitstream constraint may                     be added such that when the new SPS syntax element                     sps_intra_only_flag is equal to 1, the value of the                     inter related SPS syntax element is required to be                     equal to 0.                 -   3. In one example (in this case the PPS syntax                     elements related to the new SPS/PPS syntax elements                     are signalled or inferred), in one example, a                     bitstream constraint may be added such that when the                     new SPS syntax element sps_intra_only_flag is equal                     to 1, or, the new PPS syntax element                     pps_intra_only_flag is equal to 1, the value of                     inter-related PPS syntax elements is required to be                     equal to 0.                 -   4. In one example (in this case the PH/SH syntax                     elements related to the new SPS/PPS syntax elements                     are signalled or inferred), a bitstream constraint                     may be added such that when the new SPS syntax                     element sps_intra_only_flag is equal to 1 and/or the                     new PPS syntax element pps_intra_only_flag is equal                     to 1, the value of the corresponding inter-related                     and/or RPL-related syntax element included in PH/SH                     is required to be equal to a certain value (such as                     0 or 1). -   6. Regarding adding new general constraint flags/fields for solving     the sixth problem:     -   1) In the syntax general_constraint_info( ), new general         constraint flags may be added, and furthermore, these new         general constraint flags may be used to condition the related         syntax elements in SPS/PPS/PH/SH, or to constrain the values of         related syntax elements in SPS/PPS/PH/SH through bitstream         constraints, e.g., as in the fifth embodiment.         -   a. For example, a new general constraint flag may be added             to achieve one or more functionalities as described below.             -   i. For example, add a new general constraint flag to                 disable the inter-layer prediction and/or allowing only                 one layer, e.g., a new syntax element                 no_inter_layer_prediction_constraint_flag is added.                 Furthermore, this new syntax element may be used to                 condition the signalling of the SPS syntax element                 inter_layer_ref_pics_present_flag or to constrain its                 value.             -   ii. For example, add a new general constraint flag to                 disable long-term reference, e.g., a new syntax element                 no long_term_ref_pics_constraint_flag. Furthermore, this                 new syntax element may be used to condition the                 signalling of the SPS syntax element                 long_term_ref_pics_flag or to constrain its value.             -   iii. For example, add a new general constraint flag to                 disable max transform size equal to 32×32, e.g., a new                 syntax element no_max_luma_transform_size                 64_constraint_flag. Furthermore, this new syntax element                 may be used to condition the signalling of the SPS                 syntax element sps_max_luma_transform_size_64_flag or to                 constrain its value.             -   iv. For example, add a new general constraint flag to                 disable MER, e.g., a new syntax element                 no_parallel_merge_level_constraint_flag. Furthermore,                 this new syntax element may be used to condition the                 signalling of the SPS syntax element                 log2_parallel_merge_level_minus2 or to constrain its                 value.             -   v. For example, add a new general constraint flag to                 disable the presence of the wavefront parallel                 processing entry offsets, e.g., a new syntax element                 no_wpp_entry_point_offset_present_constraint_flag.                 Furthermore, this new syntax element may be used to                 condition the signalling of the SPS syntax element                 sps_wpp_entry_point_offsets_present_flag or to constrain                 its value.             -   vi. For example, add a new general constraint flag to                 disable the entropy coding sync point (i.e., wavefront                 parallel processing), e.g., a new syntax element                 no_entropy_coding_sync_constraint_flag. Furthermore,                 this new syntax element may be used to condition the                 signalling of the SPS syntax element                 sps_entropy_coding_sync_enabled_flag or to constrain its                 value.         -   b. For example, a new general constraint flag may be added             to control one or more of the coding tools as described             below.             -   i. For example, add a new general constraint flag to                 disable weighted prediction for P slices, e.g., a new                 syntax element no_weighted_pred_constraint_flag.                 Furthermore, this new syntax element may be used to                 condition the signalling of the SPS syntax element                 sps_weighted_pred_flag or to constrain its value.             -   ii. For example, add a new general constraint flag to                 disable the weighted bi-prediction for B slices, e.g., a                 new syntax element no_wighted_bipred_constraint_flag.                 Furthermore, this new syntax element may be used to                 condition the signalling of the SPS syntax element                 sps_weighted_bipred_flag or to constrain its value.             -   iii. For example, add a new general constraint flag to                 disable the SMVD, e.g., a new syntax element                 no_smvd_constraint_flag. Furthermore, this new syntax                 element may be used to condition the signalling of the                 SPS syntax element sps_smvd_enabled_flag or to constrain                 its value.             -   iv. For example, add a new general constraint flag to                 disable the MMVD, e.g., a new syntax element                 no_mmvd_constraint_flag. Furthermore, this new syntax                 element may be used to condition the signalling of the                 SPS syntax element sps_mmvd_enabled_flag or to constrain                 its value.             -   v. For example, add a new general constraint flag to                 disable the ISP, e.g., a new syntax element                 no_isp_constraint_flag. Furthermore, this new syntax                 element may be used to condition the signalling of the                 SPS syntax element sps_isp_enabled_flag or to constrain                 its value.             -   vi. For example, add a new general constraint flag to                 disable the MRL, e.g., a new syntax element                 no_mrl_constraint_flag. Furthermore, this new syntax                 element may be used to condition the signalling of the                 SPS syntax element sps_mrl_enabled_flag or to constrain                 its value.             -   vii. For example, add a new general constraint flag to                 disable the MIP, e.g., a new syntax element                 no_mip_constraint_flag. Furthermore, this new syntax                 element may be used to condition the signalling of the                 SPS syntax element sps_mip_enabled_flag or to constrain                 its value.             -   viii. For example, add a new general constraint flag to                 disable the PLT, e.g., a new syntax element                 no_palette_constraint_flag. Furthermore, this new syntax                 element may be used to condition the signalling of the                 SPS syntax element sps_palette_enabled_flag or to                 constrain its value.             -   ix. For example, add a new general constraint flag to                 disable the ACT, e.g., a new syntax element                 no_act_constraint_flag. Furthermore, this new syntax                 element may be used to condition the signalling of the                 SPS syntax element sps_act_enabled_flag or to constrain                 its value.             -   x. For example, add a new general constraint flag to                 disable the LMCS, e.g., a new syntax element                 no_lmcs_constraint_flag. Furthermore, this new syntax                 element may be used to condition the signalling of the                 SPS syntax element sps_lmcs_enabled_flag or to constrain                 its value.             -   xi. For example, add a new general constraint flag to                 disable the LFNST, e.g., a new syntax element                 no_lfnst_constraint_flag. Furthermore, this new syntax                 element may be used to condition the signalling of the                 SPS syntax element sps_lfnst_enabled_flag or to                 constrain its value.             -   xii. For example, add a new general constraint flag to                 disable the scaling list, e.g., a new syntax element                 no_scaling_list_constraint_flag. Furthermore, this new                 syntax element may be used to condition the signalling                 of the SPS syntax element sps_scaling_list_enabled_flag                 or to constrain its value.             -   xiii. For example, add a new general constraint flag to                 disable the virtual boundaries, e.g., a new syntax                 element no_virtual_boundaries_constraint_flag.                 Furthermore, this new syntax element may be used to                 condition the signalling of the SPS syntax element                 sps_virtual_boundaries_enabled_flag or to constrain its                 value.         -   c. For example, a new general constraint flag may be added             to control (i.e., to condition the signalling of or to             constrain the values of) a group of syntax elements as             described below.             -   i. For example, add a new general constraint flag to                 disable the weighted prediction and weighted                 bi-prediction. Furthermore, this new syntax element may                 be used to control the SPS syntax elements                 sps_weighted_pred_flag and sps_weighted_bipred_flag.         -   d. For example, when the new general constraint syntax is             equal to 1, the signalling of the corresponding SPS/PH/SH             syntax element may be skipped.             -   ii. Additionally, when the corresponding SPS/PH/SH                 syntax element is not present (in the case of the                 corresponding new general constraint syntax element is                 equal to 1), the value of the corresponding SPS/PH/SH                 syntax element is inferred to be equal to a certain                 value (such as 0 or 1).             -   iii. Alternatively (in this case of the corresponding                 SPS/PH/SH syntax element is signalled or inferred), in                 one example, a bitstream constraint may be added such                 that when the new general constraint syntax element is                 equal to 1, the value of the corresponding SPS/PH/SH                 syntax element is required to be equal to a certain                 value (such as 0 or 1).             -   i. Alternatively, in one example, when                 no_aps_cosntraint_flag is equal to 1, the values of the                 APS-related newly added constraint flags (e.g.,                 no_scaling_list_constraint_flag and                 no_lmcs_constraint_flag) are required to be equal to 1.             -   ii. Alternatively, in one example, when                 intra_only_cosntraint_flag is equal to 1, the values of                 the APS-related newly added constraint flags (e.g.,                 no_weighted_pred_constraint_flag,                 no_weighted_bipred_constraint_flag,                 no_long_term_ref_pics_constraint_flag,                 no_inter_layer_prediction_constraint_flag,                 no_smvd_constraint_flag, and no_mmvd_constraint_flag)                 are required to be equal to 1.             -   iii. Alternatively, in one example, when                 vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]]                 is equal to 1, the value of                 no_inter_layer_prediction_constraint_flag is required to                 be equal to 1. -   7. Regarding the connection of APS syntax elements to the syntax     elements in the other parameter sets for solving the seventh     problem:     -   1) In one example, VPS ID and/or SPS ID and/or PPS ID may be         added to APS syntax structure, i.e.,         adaptation_parameter_set_rbsp( ), e.g., as in the sixth         embodiment.     -   2) In one example, the APS syntax elements (e.g.,         alf_luma_filter_signal_flag, alf_chroma_filter_signal_flag,         alf_cc_cb_filter_signal_flag and alf_cc_cr_filter_signal_flag)         may be dependent on the value of general constraint flag, e.g.,         as in the sixth embodiment.         -   a. For example, when no_aps_constraint_flag is equal to 0,             at least one of the values of alf_luma_filter_signal_flag,             alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag             and alf_cc_cr_filter_signal_flag shall be equal to 1.         -   b. For example, when sps_alf_enabled_flag is equal to 1, at             least one of the values of alf_luma_filter_signal_flag,             alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag             and alf_cc_cr filter_signal_flag shall be equal to 1.         -   c. When no_aps_constraint_flag is equal to 0 and             sps_alf_enabled_flag is equal to 1, at least one of the             values of alf_luma_filter_signal_flag,             alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag             and alf_cc_cr_filter_signal_flag shall be equal to 1.         -   d. Alternatively, the values of alf_luma_filter_signal_flag,             alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag             and alf_cc_cr_filter_signal_flag may dependent on whether             there is a APS NAL unit having aps_params_type equal to             ALF_APS.     -   3) In one example, the APS syntax elements may be dependent on         the value of a syntax element associated with the corresponding         SPS/PPS according to the SPS/PPS ID.         -   a. For example, the value of chroma-related APS syntax             elements (such as alf_chroma_filter_signal_flag,             alf_cc_cb_filter_signal_flag, alf_cc_cr_filter_signal_flag,             scaling_list_chroma_present_flag, and etc) may be not             constrained according to variables (such as ChromaArrayType)             derived by the SPS syntax elements.     -   4) In one example, bitstream constraints may be added that when         no_aps_constraint_flag is equal to 1, the syntax elements         associated with the syntax structures alf_data( ), lmcs_data( ),         and scaling_list_data( ) cannot be sent. -   8. Regarding redundant signalling of the general constraint flags:     -   1) In one example, indicators may be included in the syntax         structures of profile_tier_level( ) and/or         general_constraint_info( ), to indicate which profile and/or         which tier and/or which level that the current general         constraint information applies to.     -   2) In one example, the syntax structure general_constraint_info(         ) may be and may only be included in the SPS syntax structure         seq_parameter_set_rbsp( ).     -   3) Bitstream constraint may be added that if there is VPS, the         general_constraint_info( ) syntax elements included in VPS are         used for the CVS.     -   4) Bitstream constraint may be added that if there is NO VPS,         the general_constraint_info( ) syntax elements included in SPS         are use for the current CLVS. -   9. In one example, whether and/or how to signal the general     constraint structure may depend on the values of the profile and/or     the sub-profiles and/or level and/or tier.     -   a. In one example, each general_constraint_info( ) syntax         structure is specified to be associated with one set of         general_profile_idc and subprofile_sub_profile_idc[i] for all i         values signalled in the same profile_tier_level( ) syntax         structure as the general_constraint_info( ) syntax structure.         -   Or equivalently, each general_constraint_info( ) syntax             structure is specified to be associated with the             profile_tier_level( ) syntax structure containing the             general_constraint_info( ) syntax structure.     -   b. In one example, the information carried in a         general_constraint_info( ) syntax structure may impose more         constraints regarding which coding tools can be applied than the         profile and sub-profiles indicated in the profile_tier_level( )         syntax structure containing the general_constraint_info( )         syntax structure. That means, in addition to all the constraints         imposed by the profile and sub-profiles, more aspects may be         constrained by the general constraint information.     -   c. In one example, for any particular aspect associated with a         general constraint syntax element, the corresponding general         constraint syntax element has to have a value that indicates         either a tighter constraint regarding that aspect than indicated         by the profile and sub-profiles or the same constraint regarding         that aspect as indicated by the profile and sub-profiles.         -   i. In one example, if any of the profile and sub-profiles             indicates that all slices are intra slices, then the             intra_only_constraint_flag shall be equal to 1, whereas if             none of the profile and sub-profiles indicates that all             slices are intra slices, the intra_only_constraint_flag may             be equal to either 1 or 0.     -   d. In one example, for any particular aspect associated with a         general constraint syntax element, the tightest constraint         indicated by the profile, the sub-profiles, and the         corresponding general constraint syntax element applies.         -   i. In one example, when any of the profile and sub-profiles             indicates that all slices are intra slices, the value of             intra_only_constraint_flag may be equal to either 1 or 0,             but still all slices are required to be intra slices, and             when none of the profile and sub-profiles indicates that all             slices are intra slices and the value of             intra_only_constraint_flag is equal to 1, again all slices             are required to be intra slices.     -   e. In one example, no general constraint information is signaled         for a specific profile and/or sub-profile and/or level and/or         tier. The general constraint flags/fields are inferred to be         predefined values based on the specific profile and/or level         and/or tier.     -   f. In one example, the general constraint information may be         signaled but ignored for a specific profile and/or sub-profile         and/or level and/or tier. The general constraint flags are         inferred to be predefined values based on the specific profile         and/or level and/or tier.     -   g. In one example, the general constraint information may be         signaled for a specific profile and/or sub-profile and/or level         and/or tier. The general constraint flags must be equal to         predefined values based on the specific profile and/or level         and/or tier in a conformance bitstream.     -   h. In one example, the general constraint information may be         signaled for a specific profile and/or sub-profile and/or level         and/or tier. Whether and/or how to apply a coding tool may be         determined by the corresponding general constraint flag(s),         ignoring the specification in the profile and/or level and/or         tier.     -   i. In one example, the general constraint flag associated with a         coding tool must be set equal to 1 (meaning turned oft) if the         coding tool is specified to be turned off in the profile and/or         sub-profile and/or level and/or tier.     -   j. In one example, the general constraint flag associated with a         coding tool may be ignored and inferred to be 1 (meaning turned         oft) if the coding tool is specified to be turned off in the         profile and/or sub-profile and/or level and/or tier.     -   k. In one example, the general constraint flag associated with a         coding tool may be skipped and inferred to be 1 (meaning turned         off) if the coding tool is specified to be turned off in the         profile and/or sub-profile and/or level and/or tier.     -   l. In one example, for a profile and/or sub-profile a         sub-profile indicating all intra coding,         intra_only_constraint_flag must be equal to 1.         -   i. Alternatively, for a profile and/or sub-profile a             sub-profile indicating all intra coding,             intra_only_constraint_flag is skipped or ignored and             inferred to be 1. -   10. Regarding the presence and the value of the syntax element     (e.g., X_info_in_ph_flag in the PPS), for solving the eighth     problem:     -   a. It is proposed that the presence of the syntax element (e.g.,         X_info_in_ph_flag in the PPS), specifying whether the associated         information of a certain feature is signalled in the PH or SH,         is conditioned on whether there is partition/split of the         pictures referring to the PPS (e.g., whether         no_pic_partition_flag is equal to 1).         -   i. Alternatively, the presence of X_info_in_ph_flag in the             PPS may be conditioned on whether there is only one slice in             the pictures referring to the PPS.         -   ii. Additionally, infer X_info_in_ph_flag to be equal to a             certain value (such as 0 or 1) when not present.             -   1. Alternatively, if the feature X is dependent on the                 APS syntax elements, then infer X_info_in_ph_flag to be                 equal to 1 when not present.             -   2. Alternatively, if the feature X is not dependent on                 the APS syntax elements, then infer X_info_in_ph_flag to                 be equal to 0 when not present.     -   b. Additionally, the value of X_info_in_ph_flag may be         constrained based on whether PH syntax structure is present in         the slice header.         -   i. For example, it is required that, when             picture_header_in_slice_header_flag is equal to 1, the value             of X_info_in_ph_flag is required to be equal to a certain             value (such as 0 or 1).     -   c. For example, X may be chroma QP offsets (suppose a flag named         chroma_qp_offset_info_in_ph_flag is signalled in the PPS to         control whether to signal chroma QP offsets in the PH or SH).     -   d. For example, X may be any feature whose associated         information could be signalled either in the PH or SH. -   11. Regarding removing the semantics dependency of APS on SPS, for     solving the ninth problem:     -   a. In one example, a syntax element (e.g., named         aps_chroma_present_flag) may be signalled in the APS syntax         structure (e.g., adaptation_parameter_set_rbsp( )) specifying         whether the chroma-related APS syntax elements would be         signalled or not     -   b. For example, ChromaArrayType derived by SPS syntax elements         is achievable through the SPS/PPS ID associated with the PH/SH         syntax elements.     -   c. In one example, the constraints of APS syntax elements (e.g.,         aps_chroma_present_flag) may be dependent on variables (e.g.,         ChromaArrayType) derived from the PH or SH syntax elements.     -   d. In one example, the constraints and signalling are applied as         in the seventh embodiment.     -   e. In one example, the constraints and signalling are applied as         in the eighth embodiment.     -   f. For example, it is required that, the value of         aps_chroma_present_flag of the APS NAL unit having         aps_params_type equal to ALF_APS and adaptation_parameter_set_id         equal to ph_alf_aps_id_luma[i] shall be equal to 1 when         chromaArrayType is not equal to 0.         -   i. Alternatively, it is required that, the value of             aps_chroma_present_flag of the APS NAL unit having             aps_params_type equal to ALF_APS and             adaptation_parameter_set_id equal to ph_alf aps_id_chroma             shall be equal to 1 when chromaArrayType is not equal to 0.         -   ii. Alternatively, additionally, it is required that, the             value of aps_chroma_present_flag of the APS NAL unit having             aps_params_type equal to ALF_APS and             adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_id             shall be equal to 1 when chromaArrayType is not equal to 0.         -   iii. Alternatively, additionally, it is required that, the             value of aps_chroma_present_flag of the APS NAL unit having             aps_params_type equal to ALF_APS and             adaptation_parameter_set_id equal to ph_cc_alf_cr_aps_id             shall be equal to 1 when chromaArrayType is not equal to 0.     -   g. Additionally, it is required that, the value of         aps_chroma_present_flag of the APS NAL unit having         aps_params_type equal to ALF_APS and adaptation_parameter_set_id         equal to ph_alf_aps_id_luma[i] shall be equal to 0 when         chromaArrayType is equal to 0.     -   h. Additionally, it is required that, the value of         aps_chroma_present_flag of the APS NAL unit having         aps_params_type equal to ALF_APS and adaptation_parameter_set_id         equal to slice_alf_aps_id_luma[i] shall be equal to 1 when         chromaArrayType is not equal to 0.         -   i. Alternatively, it is required that, the value of             aps_chroma_present_flag of the APS NAL unit having             aps_params_type equal to ALF_APS and             adaptation_parameter_set_id equal to slice_alf_aps_id_chroma             shall be equal to 1 when chromaArrayType is not equal to 0.         -   ii. Alternatively, additionally, it is required that, the             value of aps_chroma_present_flag of the APS NAL unit having             aps_params_type equal to ALF APS and             adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_id             shall be equal to 1 when chromaArrayType is not equal to 0.         -   iii. Alternatively, additionally, it is required that, the             value of aps_chroma_present_flag of the APS NAL unit having             aps_params_type equal to ALF_APS and             adaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id             shall be equal to 1 when chromaArrayType is not equal to 0.     -   i. Additionally, it is required that, the value of         aps_chroma_present_flag of the APS NAL unit having         aps_params_type equal to ALF_APS and adaptation_parameter_set_id         equal to slice_alf_aps_id_luma[i] shall be equal to 0 when         chromaArrayType is equal to 0. -   12. It is proposed that a SE (e.g. named as     “general_pic_header_in_slice_header_constraint_flag”) is signaled in     the general constrained syntax structure (such as     general_constraint_info( ) in VVC) to indicate whether picture     header information shall be signaled in the slice header.     -   a. For example, it is required that picture header information         shall be signaled in the slice header when         general_pic_header_in_slice_header_constraint_flag is equal to         0.     -   b. For example, it is required that picture header information         shall be signaled in the slice header when         general_pic_header_in_slice_header_constraint_flag is equal to         1.     -   c. It is required that the SE (such as         one_slice_per_pic_constraint_flag), which indicates whether each         picture shall contain only one slice, shall be equal to 1 when         general_pic_header_in_slice_header_constraint_flag is equal to         0.     -   d. It is required that the SE (such as         one_slice_per_pic_constraint_flag), which indicates whether each         picture shall contain only one slice, shall be equal to 1 when         general_pic_header_in_slice_header_constraint_flag is equal to         1. -   13. It is proposed that whether to allow partition a picture into     rectangular slices or non-rectangular slices may be constrained by a     bitstream conformance.     -   a. Alternatively, whether to signal a picture header in a slice         header may be constrained by a bitstream conformance depending         on whether to partition a picture into rectangular slices or         non-rectangular slices     -   b. For example, a SE (such as         picture_header_in_slice_header_flag) indicating whether to         signal a picture header in a slice header shall be equal to 1         when partitioning a picture into rectangular slices (e.g.         rect_slice_flag is equal to 1).     -   c. For example, a SE (rect_slice_flag) indicating whether to         partition a picture into rectangular slices shall be equal to 1         when signaling a picture header in a slice header (e.g.         picture_header_in_slice_header_flag is equal to 1). -   14. Regarding the GCI syntax structure signalling for solving the     10^(th) problem, one or more of the following approaches are     disclosed, e.g., as in the ninth embodiment:     -   a. A new syntax element (e.g., a flag, named gci_present_flag)         is signalled in the profile_tier_level( ) syntax structure to         indicate the presence of the GO SEs in the GCI syntax structure         (e.g., general_constraint_info( )) and/or the presence of the         GCI syntax structure (e.g., general_constraint_info( )) itself         in the PTL syntax structure (e.g. profile_tier_level( )).         -   i. In one example, whether the GCI SEs in the GCI syntax             structure are signalled or not are conditioned on the value             of gci_present_flag.         -   ii. In one example, if the syntax element specifies that the             GCI is not present (e.g., gci_present_flag is equal to 0),             then the GCI syntax structure (e.g.,             general_constraint_info( )) is not signalled in the current             profile_tier_level( ) syntax structure.         -   iii. In one example, when the GO syntax structure is not             present in a profile_tier_level( ) syntax structure, or the             GCI SEs in the GCI syntax structure are not present, it is             specified that each of the GCI SEs is inferred to be the             value such that the corresponding constraint is not imposed.             For example, the value of the intra_only_constraint_flag is             inferred to be equal to 0.             -   1. In one example, the following inference is specified:                 When gci_present_flag equal to 0 for a                 profile_tier_level( ) syntax structure with                 profileTierPresentFlag equal to 1 (and therefore the GCI                 syntax structure is not present in the                 profile_tier_level( ) syntax structure), the value of                 max_bitdepth_constraint_idc is inferred to be equal to                 8, the vlaue of max_chroma_format_constraint_idc is                 inferred to be equal to 3, and the value of the each of                 the other syntax elements in the                 general_constraint_info( ) syntax structure starting                 from general_non_packed_constraint_flag to                 no_aps_constraint_flag, inclusive, is inferred to be                 equal to 0.         -   iv. In one example, when a GCI SE is not signaled, it may be             inferred to be a default value, such as 0 or 1.             -   1. The default value may depend on profiles and/or                 levels.             -   v. In one example, the signaling of gci_present_flag may                 be conditioned on profiles and/or levels.                 -   1. When gci_present_flag is not signaled, it may be                     inferred to be a default value, such as 0 or 1.             -   vi. In one example, gci_present_flag is u(1) coded.     -   b. The starting position of the syntax element that specifies a         level to which OlsInScope conforms (e.g., general_level_idc) is         always a byte-aligned position.         -   i. In one example, if the current position in the bitstream             is not on a byte boundary, i.e., the next bit in the             bitstream is not the first bit in a byte, then one or more             syntax elements (e.g., ptl_alignment_zero_bit) are signalled             right before general_level_idc until the starting position             is byte aligned.             -   1. In one example, 0-valued syntax element (e.g.,                 ptl_alignment_zero_bit) is coded with a fixed-pattern                 bit string using n bits written (from left to right)                 with the left bit first, wherein n=1, a.k.a, f(1) coded.     -   c. The GCI syntax structure may be not byte aligned.         -   i. In one example, general constraint flags are signalled in             the GCI syntax structure, without checking if they are byte             aligned or not.     -   d. Reserved bits are signalled in the GCI syntax structure.         -   i. In one example, the number of reserved bits is signalled             in the GCI syntax structure, e.g., named             gci_num_reserved_bits.         -   ii. In one example, the number of reserved bits signalled in             the GCI syntax structure is u(N) coded, such as N=11.         -   iii. In one example, the number of reserved bits signalled             in the GCI syntax structure is ue(v) coded.         -   iv. In one example, reserved GCI syntax element (e.g., named             gci_reserved_bit[i]) is signalled, wherein i ranges from 0             to gci_num_reserved_bits−1, inclusive.         -   v. In one example, reserved GCI syntax element is u(X)             coded, such as X=1.         -   vi. In one example, the reserved bits must be byte-aligned.             -   1. In one example, the number of bytes of the reserved                 bits is signaled -   15. Regarding the semantics constraints of general constraint     flags/fields for solving the 11^(th) problem, one or more of the     following approaches are disclosed, e.g., as in the ninth     embodiment:     -   a. In one example, when only slice_type equal to 1_SLICE is         allowed (e.g., intra_only_constraint_flag is equal to 1), one or         more constraints in the following may be specified:         -   i. RPL-related SEs are constrained to a certain value that             specifying the RPL is required to be not used.         -   ii. Long term reference picture is required to be not             allowed (e.g., the value of long_term_ref_pics_flag shall be             equal to 0).         -   iii. RPL is required to be not allowed for IDR pictures             (e.g., the value of sps_idr_rpl_present_flag shall be equal             to 0).         -   iv. The number of reference picture lists is required to be             equal to 0 (e.g., the value of sps_num_ref_pic_lists[i]             shall be equal to 0).         -   v. All layers shall be independent layers (e.g., the value             of all_layers_independent_constraint_flag shall be equal to             1).         -   vi. RPR is required to be not allowed (e.g., the value of             no_ref_pic_resampling_constraint_flag shall be equal to 1).         -   vii. Resolution change is required to be not allowed (e.g.,             the value of no_res_change_in_clvs_constraint_flag shall be             equal to 1).         -   viii. Weighted prediction for P slices is required to be not             allowed.             -   1. A new syntax element (e.g., named                 no_weighted_pred_constraint_flag) may be signalled in                 the GCI syntax structure to indicate whether weighted                 prediction for P slices shall be allowed or not.             -   2. In one example, when only slice_type equal to I_SLICE                 is allowed (e.g., intra_only_constraint_flag is equal to                 1), the value of no_weighted_bipred_constraint_flag                 shall be equal to 1.         -   ix. Weighted prediction for B slices is required to be not             allowed.             -   1. A new syntax element (e.g., named                 no_weighted_bipred_constraint_flag) may be signalled in                 the GO syntax structure to indicate whether weighted                 prediction for B slices shall be allowed or not.             -   2. In one example, when only slice_type equal to I_SLICE                 is allowed (e.g., intra_only_constraint_flag is equal to                 1), the value of no_weighted_bipred_constraint_flag                 shall be equal to 1.         -   x. Weighted predictions for both P slices and B slices are             required to be not allowed.             -   1. A new syntax element (e.g., named                 no_weighted_pred_constraint_flag) may be signalled in                 the GCI syntax structure to indicate whether weighted                 prediction for P and B slices shall be allowed or not.             -   2. In one example, when only slice_type equal to I_SLICE                 is allowed (e.g., intra_only_constraint_flag is equal to                 1), the value of no_weighted_pred_constraint_flag shall                 be equal to 1.         -   xi. SBT is required to be not allowed (e.g., the value of             no_sbt_constraint_flag shall be equal to 1).         -   xii. GDR is required to be not allowed (e.g., the value of             no_gdr_constraint_flag shall be equal to 1).         -   xiii. A coding tool X which is applied on inter pictures             only is not allowed. E.g., the value of a constraint flag             no_X_constraint_flag shall be equal to             -   1. For example, X_flag may be one of:                 -   1. no_ref_wraparound_constraint_flag                 -   2. no_temporal_mvp_constraint_flag                 -   3. no_sbtmvp_constraint_flag                 -   4. no_amvr_constraint_flag                 -   5. no_bdof_constraint_flag                 -   6. no_dmvr_constraint_flag                 -   7. no_affine_motion_constraint_flag                 -   8. no_mmvd_constraint_flag                 -   9. no_smvd_constraint_flag                 -   10. no_prof_constraint_flag                 -   11. no_bcw_constraint_flag                 -   12. no_ciip_constraint_flag                 -   13. no_gpm_constraint_flag     -   b. The SEs in the SPS/PPS/PH/SH may be constrained by the GCI         SEs.         -   i. In one example, when each picture only contains one tile             (e.g., one_tile_per_pic_constraint_flag is equal to 1), one             or more constraints in the following may be specified:             -   1. The number of tile columns is required to be 1 (e.g.,                 the value of pps_num_exp_tile_columns_minus1 shall be                 equal to 0).             -   2. The number of tile rows is required to be 1 (e.g.,                 the value of pps_num_exp_tile_rows_minus1 is inferred to                 be equal to 0).             -   3. The slices are required to be rectangular slices                 other than raster-scan slices (e.g., the value of                 pps_rect_slice_flag shall be equal to 1).         -   ii. In one example, when APS is required to be not allowed             (e.g., no_aps_constraint_flag is equal to 1), one or more             constraints in the following may be specified:             -   1. CCALF is required to be not allowed (e.g.,                 sps_ccalf_enabled_flag shall be equal to 0).             -   2. The number of ALF luma APS is required to be equal to                 1 (e.g., ph_num_alf_aps_ids_luma,                 slice_num_alf_aps_ids_luma shall be equal to 0).             -   3. chroma ALF is required to be not allowed (e.g.,                 ph_alf_cb_flag, ph_alf_cr_flag, sh_alf_cb_flag, and                 sh_alf_cr_flag shall be equal to 0).         -   iii. In one example, when each picture only contains one             slice (e.g., one_slice_per_pic_constraint_flag is equal to             1), The slices are required to be rectangular slices other             than raster-scan slices (e.g., the value of             pps_rect_slice_flag shall be equal to 1).         -   iv. In one example, when each picture only contains one tile             and each picture only contains one slice (e.g.,             one_tile_per_pic_constraint_flag and             one_slice_per_pic_constraint_flag are both equal to 1),             there shall be no picture partition (e.g., the value of             pps_no_pic_partition_flag shall be equal to 1).         -   v. In one example, when each picture only contains one slice             and the slice is rectangular slice (e.g.,             one_slice_per_pic_constraint_flag and rect_slice_flag are             both equal to 1), then the number of slices in the picture             is required to be equal to 1 (e.g., the value of             pps_num_slices_in_pic_minus1 shall be equal to 0).         -   vi. In one example, when each picture only contains one             subpicture (e.g., one_subpic_per_pic_constraint_flag equal             to 1), it specifies that the number of subpictures is             required to be equal to 1 (e.g., sps_num_subpics_minus1             shall be equal to 0).     -   c. Some GCI SEs may be constrained by other GCI SEs.         -   i. In one example, when             all_layers_independent_constraint_flag is equal to 1, the             value of sps_inter_layer_ref_pics_present_flag shall be             equal to 0.         -   ii. When no_transform_skip_constraint_flag is equal to 1,             the value of no_bdpcm_constraint_flag shall be equal to 1.         -   iii. When no_lmcs_constraint_flag or             no_explicit_scaling_list_constraint_flag or             no_ccalf_constraint_flag is equal to 0, the value of             no_aps_constraint_flag shall be equal to 0.     -   d. The definition of intra_only_constraint_flag considers the         nuh_layer_type for each coded slice NAL unit.         -   i. In one example, intra_only_constraint_flag equal to 1             specifies that sh_slice_type shall be equal to 1 and             nuh_layer_type for each coded slice NAL unit shall be             IDR_N_LP. -   16. Whether to signal and/or how to signal/derive the values of a     GCI SE may be dependent on profile and/or level information.     -   e. In one example, a GCI SE may be constrained by profiles         and/or levels.         -   i. For example, a GCI SE may be required to be a specific             value (e.g. 0 or 1) for a specific profile and/or level.     -   f. In one example, a GCI SE may be conditionally signalled         according to profiles and/or levels.         -   i. In one example, the GCI SE is not signalled when the             profile and/or level doesn't satisfy a rule.             -   1. Alternatively, furthermore, when not present, the GCI                 SE may be inferred to be a value X (e.g., X being 0 or                 1).             -   2. Alternatively, furthermore, when not present, the GCI                 SE may be inferred to be a value which is dependent on                 the profile and/or level. -   17. Regarding the aps_chroma present flag in case of SCALING APS for     solving the 12^(th) problem, one or more of the following approaches     are disclosed:     -   g. The scaling list APS ID could be signalled for luma and         chroma, respectively.         -   i. In one example, two syntax elements may be signaled in             the PH/SH, to specify the scaling list APS ID for luma and             chroma, respectively.         -   ii. In one example, three syntax elements may be signaled in             the PH/SH, to specify the scaling list APS ID for each color             component, respectively.     -   h. The chroma scaling list may be not signaled even for 4:2:0         and/or 4:2:2 and/or 4:4:4 chroma formats.         -   i. Alternatively, furthermore, default scaling matrix is             used for processing chroma components.         -   i. Whether to signal the scaling list SEs for chroma may be             dependent on the chroma formats.         -   i. In one example, for 4:0:0 and/or separate-color-plane             coding, the chroma scaling list SEs are required to be NOT             signaled.         -   ii. In one example, for 4:2:0 and/or 4:2:2 and/or 4:4:4             coding, the chroma scaling list SEs may be or may be not             signaled.

6. Embodiments

Below are some example embodiments for some of the invention aspects summarized above in Section 5, which can be applied to the VVC specification. The changed texts are based on the latest VVC text in JVET-Q2001-vC Most relevant parts that have been added or modified are highlighted in bold and Italic, and some of the deleted parts are marked with double brackets (e.g., [[a]] denotes the deletion of character “a”).

6.1. First Embodiment

This is an embodiment of items 1, 1.1, 1.1a, 1.1b, and 1.1.c summarized above in Section 5.

6.1.1. Embodiment of Items 2.1 and 2.1a

In one example, the syntax structure seq_parameter_set_rbsp( ) is changed as follows:

seq_parameter_set_rbsp( ) { Descriptor  sps_seq_parameter_set_id  u (4)  sps_video_parameter_set_id  u (4)  sps_max_sublayers_minus1  u (3)  sps_reserved_zero_4bits  u (4)  sps_pt_dpb_hrd_params_present_flag  u (1)  if( sps_ptl_dpb_hrd_params_present_flag )   profile_tier_level( 1, sps_max_sublayers_minus1 )  

  gdr_enabled_flag  u (1)  

  chroma_format_idc  u (2)  if( chroma_format_idc = = 3 )   separate_colour_plane_flag  u (1)  

  res_change_in_clvs_allowed_flag  u (1)  pic_width_max_in_luma_samples ue (v)  pic_height_max_is_luma_samples ue (v)  sps_conformance_window_flag  u (1)  if( sps_conformance_window_flag ) {   sps_conf_win_left_offset ue (v)   sps_conf_win_right_offset ue (v)   sps_conf_win_top_offset ue (v)   sps_conf_win_bottom_offset ue (v)  }  sps_log2_cta_size_minus5  u (2)  subpic_info_present_flag  u (1)  if( subpic_info_present_flag ) {   sps_num_subpics_minus1 ue (v)   

   sps_independent_subpics_flag  u (1)   for( i = 0; sps_num_subpics_minus1 > 0 && i <= sps_num_subpics_minus1; i++ ) {    if( i > 0 && pic_width_max_in_luma_samples > CtbSizeY )     subpic_ctu_top_left_x[ i ]  u (v)    iff i > 0 && pic_height_max_in_luma_samples > CtbSizeY ) {     subpic_ctu_top_left_y[ i ]  u (v)    if( i < sps_num_subpics_minus1 &&      pic_width_max_in_luma_samples > CtbSizeY )     subpic_width_minus1 [ i ]  u (v)    if( i < sps_num_subpics_minus1 &&      pic_height_max_in_luma_samples > CtbSizeY )     subpic_height_minus1[ i ]  u (v)   if( !sps_independent_subpics_flag ) {    subpic_treated_as_pic_fiag[ i ]  u (1)    loop_filter_across_subpic_enabled_flag[ i ]  u (1)   }  }  sps_subpic_id_len_minus1 ue (v)  subpic_id_mapping_explicitly_signalled_flag  u (1)  if( subpic_id_mapping_explicitly_signalled_flag ) {   subpic_id_mapping_in_sps_flag  u (1)   if( subpic_id_mapping_in_sps_flag )    for i = 0; i <= sps_num_subpics_minus1; i++ )     sps_subpic_id[ i ]  u (v)   }  }  

  bit_depth_minus8 ue (v)  sps_entropy_coding_sync_enabled_flag  u (1)  if( sps_entropy_coding_sync_enabled_flag )   sps_wpp_entry_point_offsets_present_flag  u (1)  

  sps_weighted_pred_flag  u (1)   sps_weighted_bipred_flag  u (1)  

 log2_max_pic_order_cnt_lsb_minus4  u (4)  sps_poc_msb_flag  u (1)  if( sps_poc_msb_flag )   poc_msb_len_minus1 ue (v)  num_extra_ph_bits_bytes  u (2)  extra_ph_bits_struct( num_extra_ph_bits_bytes )  num_extra_sh_bits_bytes  u (2)  extra_sh_bits_struct( num_extra_sh_bits_bytes )  if( sps_max_sublayers_minus1 > 0 )   sps_sublayer_dpb_params_flag  u (1)  if( sps_ptl_dpb_hrd_params_present_flag )   dpb_parameters( sps_max_sublayers_minus1, sps_sublayer_dpb_params_flag )  

  long_term_ref_pics_flag  u (1)  inter_layer_ref_pics_present_flag  u (1)  

  sps_idr_rpl_present_flag  u (1)   rpl1_same_as_rpl0_flag  u (1)  

 for( i = 0; i < !rpl1_same_as_rpl0_flag ? 2 : 1; i++ ) {   num_ref_pic_lists_is_sps[ i ] ue (v)   for( j = 0; j < num_ref_pic_lists_in_sps[ i ] j++ )    ref_pic_list_struct( i, j )  }  if( ChromaArrayType != 0

  qtbtt_dual_tree_intra_flag  u (1)  log2_min_luma_coding_block_size_minus2 ue (v)  

  partition_constraints_override_enabled_flag  u (1)  sps_log2_diff_min_qt_min_ch_intra_slice_luma ue (v)  sps_max_mtt_hierarchy_depth_intra_slice_luma ue (v)  if( sps_max_mtt_hierarchy_depth_intra_slice_luma != 0 ) {   sps_log2_diff_max_bt_min_qt_intra_slice_lama ue (v)   sps_log2_diff_max_tt_min_qt_intra_slice_luma ue (v)  }  sps_log2_diff_min_qt_min_cb_inter_slice ue (v)  sps_max_mtt_hierarchy_depth_inter_slice ue (v)  if( sps_max_mtt_hierarchy_depth_inter_slice != 0 ) {   sps_log2_diff_max_bt_min_qt_inter_slice ue (v)   sps_log2_diff_max_tt_min_qt_inter_slice ue (v)  }  if( qtbtt_dual_tree_intra_flag ) {   sps_log2_diff_min_qt_mis_cb_intra_slice_chroma ue (v)   sps_max_mtt_hierarchy_depth_intra_slice_chroma ue (v)   if( sps_max_mtt_hierarchy_depth_intra_slice_chroma != 0 ) {    sps_log2_diff_max_bt_min_qt_intra_slice_chroma ue (v)    sps_log2_diff_max_tt_min_qt_intra_slice_chroma ue (v)   }  }  sps_max_luma_transform_size_64_flag  u (1)  if( ChromaArrayType != 0 ) {   

   sps_joint_cbcr_enabled_flag  u (1)   same_qp_table_for_chroma  u (1)   numQpTables = same_qp_table_for_chroma ? 1 : ( sps_joint_cbcr_enabled_flag ? 3 : 2 )   for( i = 0; i < numQpTables; i++ ) {    qp_table_start_minus26[ i ] se (v)    num_points_in_gp_table_minus1[ i ] ue (v)    for( j = 0; j <= num_points_in_qp_table_minus1[ i ]; j++ ) {     delta_qp_in_val_minus1[ i ][ j ] ue (v)     delta_ap_diff_val[ i ][ j ] ue (v)    }   }  }  

  sps_sao_enabled_flag  u (1)  

  sps_alf_enabled_flag  u (1)  if( sps_alf_enabled_flag && ChromaArrayType != 0  

 )   sps_ccalf_enabled_flag  u (1)  

  sps_transform_skip_enabled_flag  u (1)  if( sps_transform_skip_enabled_flag ) {   log2_transform_skip_max_size_minus2 ue (v)   

   sps_bdpcm_enabled_flag  u (1)  }  

  sps_ref_wraparound_enabled_flag  u (1)  

  sps_temporal_mvp_enabled_flag  u (1)  if( sps_temporal_mvp_enabled_flag

 )   sps_sbtmvp_enabled_flag  u (1)  

  sps_amvr_enabled_flag  u (1)  

  sps_bdof_enabled_flag  u (1)  if( sps_bdof_enabled_flag )   sps_bdof_pic_present_flag  u (1)  sps_smvd_enabled_flag  u (1)  

  sps_dmvr_enabled_flag  u (1)  if( sps_dmvr_enabled_flag )   sps_dmvr_pic_present_flag  u (1)  sps_mmvd_enabled_flag  u (1)  sps_isp_enabled_flag  u (1)  sps_mrl_enabled_flag  u (1)  sps_mip_enabled_flag  if( ChromaArrayType != 0

 )   sps_cclm_enabled_flag  u (1)  if( chroma_format_idc = = 1 ) {   sps_chroma_horizontal_collocated_flag  u (1)   sps_chroma_vertical_collocated_flag  u (1)  }  

  sps_mts_enabled_flag  u (1)  if( sps_mts_enabled_flag ) {   sps_explicit_mts_intra_enabled_flag  u (1)   sps_explicit_mts_inter_enabled_flag  u (1)  }  six_minus_max_num_merge_cand ue (v)  

  sps_sbt_enabled_flag  u (1)  

  sps_affine_enabled_flag  u (1)  if( sps_affine_enabled_flag ) {   five_minus_max_nam_subblock_merge_cand ue (v)   sps_affine_type_flag  u (1)   if( sps_amvr_enabled_flag )    sps_affine_amvr_enabled_flag  u (1)   sps_affine_prof_enabled_flag  u (1)   if( sps_affine_prof_enabled_flag )    sps_prof_pic_present_flag  u (1)  }  sps_palette_enabled_flag  u (1)  if( ChromaArrayType = = 3 && !sps_max_luma_transform_size_64_flag )   sps_act_esabled_flag  u (1)  if( sps_transform_skip_enabled_flag ∥ sps_palette_enabled_flag )   min_qp_prime_ts_minus4 ue (v)  

  sps_bcw_enabled_flag  u (1)  

  sps_ibc_enabled_flag  u (1)  if( sps_ibc_enabled_flag )   six_minus_max_num_ibc_merge_cand ue (v)  

  sps_ciip_enabled_flag  u (1)  if( sps_mmvd_enabled_flag 

  sps_fpei_mmvd_enabled_flag  u (1)  if( MaxNumMergeCand >= 2

 ) {   sps_gpm_enabled_flag  u (1)   if( sps_gpm_enabled_flag && MaxNumMergeCand >= 3 )    max_num_merge_cand_minus_max_num_gpm_cand ue (v)  }  

  sps_lmcs_enabled_flag  u (1)  sps_lfnst_enabled_flag  u (1)  

  sps_ladf_enabled_flag  u (1)  if( sps_ladf_enabled_flag ) {   sps_num_ladf_intervals_minus2  u (2)   sps_ladf_lowest_interval_qp_offset se (v)   for( i = 0; i < sps_num_ladf_intervals_minus2 + 1; i++ ) {    sps_ladf_qp_offset[ i ] se (v)    sps_ladf_delta_threshold_minus1[ i ] ue (v)   }  }  log2_parallel_merge_level_minus2 ue (v)  

  sps_scaling_list_enabled_flag  u (1)  

  sps_dep_quant_enabled_flag  u (1)  if( !sps_dep_quant_enabled_flag

 )   sps_sign_data_hiding_enabled_flag  u (1)  sps_virtual_boundaries_enabled_flag  u (1)  if( sps_virtual_boundaries_enabled_flag ) {   sps_virtual_boundaries_present_flag  u (1)   if( sps_virtual_boundaries_present_flag ) {    sps_num_ver_virtual_boundaries  u (2)    for( i = 0; i < sps_num_ver_virtual_boundaries; i++ )     sps_virtual_boundaries_pos_x[ i ] u (13)    sps_num_hor_virtual_boundaries  u (2)    for( i = 0; i < sps_num_hor_virtual_boundaries; i++ )     sps_virtnal_boundaries_pos_y[ i ] u (13)   }  }  if( sps_ptl_dpb_hrd_params_present_flag ) {   sps_general_hrd_params_present_flag  u (1)   if( sps_general_hrd_params_present_flag ) {    general_hrd_parameters( )    if( sps_max_sublayers_minus1 > 0 )     sps_sublayer_cpb_params_present_flag  u (1)    firstSubLayer = sps_sublayer_cpb_params_present_flag ? 0 :      sps_max_sublayers_minus1    ols_hrd_parameters( firstSubLayer, sps_max_sublayers_minus1 )   }  }  field_seq_flag  u (1)  vui_parameters_present_flag  u (1)  if( vui_parameters_present_flag )   vui_parameters( ) /* Specified in ITU-T H.SEI | ISO/IEC 23002-7 */  sps_extension_flag  u (1)  if( sps_extension_flag )   while( more_rbsp_data( ) )    sps_extension_data_flag  u (1)  rbsp_trailing_bits( ) } gdr_enabled_flag equal to 1 specifics that GDR pictures may be present in CLVSs referring to the SPS. gdr_enabled_flag equal to 0 specifies that GDR pictures are not present in CLVSs referring to the SPS.

chroma_format_idc specifies that chroma sampling relative to the luma samplings as specified n clause 6.2.

res_change_in_clvs_allowed_flag equal to 1 specifies that the picture spatial resolution may change within a CLVS referring to the SPS. res_change_in_clvs_allowed_flag equal to 0 specifies that the picture spatial resolution does not change within any CLVS referring to the SPS.

bit_depth_minus8 specifies the bit depth of the samples of the luma and chroma arrays, BitDepth, and the value of the luma and chroma quantization parameter range offset, QpBdOffset, as follows:

BitDepth=8+bit_depth_minus8  (45)

QpBdOffset=6*bit_depth_minus8  (46)

bit_depth_minus8 shall be in the range of 0 to [[8]]

sps_weighted_pred_flag equal to 1 specifies that weighted prediction may be applied to P slices referring to the SPS. sps_weighted_pred_flag equal to 0 specified that weighted prediction is not applied to P slices referring to the SPS.

sps_weighted_bipred_flag equal to 1 specifies that explicit weighted prediction may be applied to B slices referring to the SPS. sps_weighted_bipred_flag equal to 0 specifies that explicit weighted prediction is not applied to B slices referring to the SPS.

long_term_ref_pics_flag equal to 0 specifies that no LTRP is used for inter prediction of any coded picture in the CLVS. long_term_ref_pics_flag equal to 1 specifies that LTRPs may be used for inter prediction of one or more coded pictures in the CLVS.

inter_layer_ref_pics_present_flag equal to 0 specifies that no ILRP is used for inter prediction of any coded picture in the CLVS. inter_layer_ref_pic_flag equal to 1 specifies that ILRPs may be used for inter prediction of one or more coded pictures in the CLVS. When sps_video_parameter_set_id is equal to 0, the value of inter_layer_ref_pics_present_flag is inferred to be equal to 0. When vps_independent_layer_flag[GeneralLayerIdx[nub_layer_id]] is equal to 1, the value of inter_layer_ref_pics_present_flag shall be equal to 0.

sps_idr_rpl_present_flag equal to 1 specifies that reference picture list syntax elements are present in slice headers of IDR pictures. sps_idr_rpl_present_flag equal to 0 specifics that reference picture list syntax elements are not present in slice headers of IDR pictures.

rpl1_same_as_rpl0_flag equal to 1 specifies that the syntax element num_ref_pic_lists_in_sps[1] and the syntax structure ref_pic_list_struct(1, rplsIdx) are not present and the following applies:

-   -   The value of num_ref_pic_lists_in_sps[1] is inferred to be equal         to the value of num_ref_pic_lists_in_sps[0].     -   The value of each of syntax elements in ref_pic_list_struct(1,         rplsIdx) is inferred to be equal to the value of corresponding         syntax element in ref_pic_list_struct(0, rplsIdx) for rplsIdx         ranging from 0 to num_ref_pic_lists_in_sps[0]−1.         partition_constraints_override_enabled_flag equal to 1 specifies         the presence of partition_constraints_override_flag in PHs         referring to the SPS.         partition_constraints_override_enabled_flag equal to 0 specifies         the absence of partition_constraints_override_flag in PHs         referring to the SPS.         sps_sao_enabled_flag equal to 1 specifies that the sample         adaptive offset process is applied to the reconstructed picture         after the deblocking filter process. sps_sao_enabled_flag equal         to 0 specifies that the sample adaptive offset process is not         applied to the reconstructed picture after the deblocking filter         process.         sps_alf_enabled_flag equal to 0 specifies that the adaptive loop         filter is disabled. sps_alf_enabled_flag equal to 1 specifies         that the adaptive loop filter is enabled.         sps_ccalf_enabled_flag equal to 0 specifies that the         cross-component adaptive loop filter is disabled.         sps_ccalf_enabled_flag to 1 specifies that the cross-component         adaptive loop filter may be enabled.         sps_transform_skip_enabled_flag equal to 1 specifies that         transform_skip_flag may be present in the transform unit syntax.         sps_transform_skip_enabled_flag equal to 0 specifies that         transform_skip_flag is not present in the transform unit syntax.         sps_ref_wraparound_enabled_flag equal to 1 specifies that         horizontal wrap-around motion compensation is applied in inter         prediction. sps_ref_wraparound_enabled_flag equal to 0 specifies         that horizontal wrap-around motion compensation is not applied.         When the value of (CtbSizeY/MinCbSizeY+1) is greater than         (pic_width_in_luma_samples/MinCbSizeY−1), where         pic_width_in_luma_samples is the value of         pic_width_in_luma_samples in any PPS that refers to the SPS, the         value of sps_ref_wraparound_enabled_flag shall be equal to 0.         sps_temporal_mvp_enabled_flag equal to 1 specifies that temporal         motion vector predictors may be used in the CLVS.         sps_temporal_mvp_enabled_flag equal to 0 specifies that temporal         motion vector predictors are not used in the CLVS.         sps_amvr_enabled_flag equal to 1 specifies that adaptive motion         vector difference resolution is used in motion vector coding.         amvr_enabled_flag equal to 0 specifies that adaptive motion         vector difference resolution is not used in motion vector         coding.         sps_bdof_enabled_flag equal to 0 specifies that the         bi-directional optical flow inter prediction is disabled.         sps_dmvr_enabled_flag equal to 1 specifies that decoder motion         vector refinement based inter bi-prediction is enabled.         sps_dmvr_enabled_flag equal to 0 specifies that decoder motion         vector refinement based inter bi-prediction is disabled.         sps_mts_enabled_flag equal to 1 specifies that         sps_explicit_mts_intra_enabled_flag is present in the sequence         parameter set RBSP syntax and         sps_explicit_mts_inter_enabled_flag is present in the sequence         parameter set RBSP syntax. sps_mts_enabled_flag equal to 0         specifies that sps_explicit_mts_intra_enabled_flag is not         present in the sequence parameter set RBSP syntax and         sps_explicit_mts_inter_enabled_flag is not present in the         sequence parameter set RBSP syntax.         sps_sbt_enabled_flag equal to 0 specifies that subblock         transform for inter-predicted CUs is disabled.         sps_sbt_enabled_flag equal to 1 specifies that subblock         transform for inter-predicteds CU is enabled.         sps_affine_enabled_flag specifies whether affine model based         motion compensation can be used for inter prediction. If         sps_affine_enabled_flag is equal to 0, the syntax shall be         constrained such that no affine model based motion compensation         is used in the CLVS, and inter_affine_flag and         cu_affine_type_flag are not present in coding unit syntax of the         CLVS. Otherwise (sps_affine_enabled_flag is equal to 1), affine         model based motion compensation can be used in the CLVS.         sps_bcw_enabled_flag specifies whether bi-prediction with CU         weights can be used for inter prediction. If         sps_bcw_enabled_flag is equal to 0, the syntax shall be         constrained such that no bi-prediction with CU weights is used         in the CLVS, and bcw_idx is not present in coding unit syntax of         the CLVS. Otherwise (sps_bcw_enabled_flag is equal to 1),         bi-prediction with CU weights can be used in the CLVS.         sps_ciip_enabled_flag specifies that ciip_flag may be present in         the coding unit syntax for inter coding units.         sps_ciip_enabled_flag equal to 0 specifies that ciip_flag is not         present in the coding unit syntax for inter coding units         sps_fpel_mmvd_enabled_flag equal to 1 specifies that merge mode         with motion vector difference is using integer sample precision.         sps_fpel_mmvd_enabled_flag equal to 0 specifies that merge mode         with motion vector difference can use fractional sample         precision.         sps_lmcs_enabled_flag equal to 1 specifies that luma mapping         with chroma scaling is used in the CLVS. sps_lmcs_enabled_flag         equal to 0 specifies that luma mapping with chroma scaling is         not used in the CLVS.         sps_lfnst_enabled_flag equal to 1 specifies that lfnst_idx may         be present in intra coding unit syntax.         sps_lfnst_enabled_flag equal to 0 specifies that lfnst_idx is         not present in intra coding unit syntax.         sps_ladf_enabled_flag equal to 1, specifies that         sps_num_ladf_intervals_minus2.         sps_ladf_lowest_interval_qp_offset, sps_ladf_qp_offset[i], and         sps_ladf_delta_threshold_minus1[i] are present in the SPS.         sps_scaling_list_enabled_flag equal to 1 specifies that a         scaling list ns used for the scaling process for transform         coefficient sps_scaling_list_enabled_flag equal to 0 specifies         that scaling list is not used for the scaling process for         transform coefficients.         sps_dep_quant_enabled_flag equal to 0 specifies that dependent         quantization is disabled for pictures referring to the SPS.         sps_dep_quant_enabled_flag equal to 1 specifies that dependent         quantization may be enabled for pictures referring to the SPS.

6.1.2. Embodiment of Items 2.1 and 2.1b

In one example, the syntax structure picture_header_structure ( ) is changed as follows:

picture_header_structure( ) { Descriptor  gdr_or_irap_pic_flag  u (1)  if( gdr_or_irap_pic_flag )   gdr_pic_flag  u (1)  

  ph_inter_slice_allowed_flag  u (1)  if( ph_inter_slice_allowed_flag )   ph_intra_slice_allowed_flag  u (1)  non_reference_picture_flag  ph_pic_parameter_set_id ue (v)  ph_pic_order_cnt_lsb  u (v)  if( gdr_or_irap_pic_flag )   no_output_of_prior_pics_flag  u (1) ...  if( rpl_info_in_ph_flag )   ref_pic_lists() ...

6.1.3. Embodiment of Items 2.1 and 2.1c

In one example, the syntax structure slice_header ( ) is changed as follows:

slice_header( ) { Descriptor  picture_header_in_slice_header_flag  u (1)  if( picture_header_in_slice_header_flag )   picture_header_structure( )  if( subpic_info_present_flag )   slice_subpic_id  u (v) ...  if( separate_colour_plane_flag = = 1 )   colour_plane_id  u (2)  if(

 !rpl_info_in_ph_flag && ( ( nal_unit_type != IDR_W_RADL && nal_unit_type !=    IDR_N_LP ) sps_idr_rpl_present_flag ) )   ref_pic_lists( )  if(

 ( rpl_info_in_ph_flag ∥ ( ( nal_unit_type != IDR_W_RADL && nal_unit_type !=    IDR_N_LP ) ∥ sps_idr_rpl_present_flag ) ) &&    ( slice_type != I && num_ref_entries[ 0 ][ RplsIdx[ 0 ] ] > 1 ) ∥    ( slice_type = = B && num_ref_entries[ 1 ][ RplsIdx[ 1 ] ] > 1 ) ) {   nam_ref_idx_active_override_flag  u (1)   if( num_ref_idx_active_override_flag )    for( i = 0; i < ( slice_type = = B ? 2: 1 ) i++ )     if( num_ref_entries[ i ][ RplsIdx[ i ] ] > 1 )      num_ref_idx_active_minus1[ i ] ue (v)  }

6.2. Second Embodiment

This is an embodiment of items 3, and 3.1 summarized above in Section 5. In one example, the general constraint information semantics are changed as follows: intra_only_constraint_flag equal to 1 specifies that slice_type shall be equal to I. intra_only_constraint_flag equal to 0 does not impose such a constraint.

one_slice_per_pic_constraint_flag equal to 1 specifies that each picture shall contain only one slice. one_slice_per_pic_constraint_flag equal to 0 does not impose such a constraint.

one_slice_per_pic_constraint_flag equal to 1 specifies that each picture shall contain only one slice. one_slice_per_pic_constraint_flag equal to 0 does not impose such a constraint.

6.3. Third Embodiment

This is an embodiment of items 4, 4.1, 4.1.a, 4.1.b, and 4.1.c summarized above in Section 5.

6.3.1. Embodiment of Items 4.1 and 4.1a

In one example, the syntax structure general_constraint_info ( ) is changed as follows:

general_constraint_info( ) { Descriptor  general_progressive_source_flag  u (1)  general_interlaced_source_flag  u (1)  general_non_packed_constraint_flag  u (1)  general_frame_only_constraint_flag  u (1)  general_non_projected_constraint_flag  u (1)  intra_only_constraint_flag  u (1)  max_bitdepth_constraint_idc  u (4)  max_chroma_format_constraint_idc  u (2)  

  no_res_change_in_clvs_constraint_flag  u (1)  one_tile_per_pic_constraint_flag  u (1)  one_slice_per_pic_constraint_flag  u (1)  

  one_subpic_per_pic_constraint_flag  u (1)  no_gtbtt_dual_tree_intra_constraint_flag  u (1)  no_partition_constraints_override_constraint_flag  u (1)  no_sao_constraint_flag  u (1)  no_alf_constraint_flag  u (1)  no_ccalf_constraint_flag  u (1)  no_joint_cbcr_constraint_flag  u (1)  

  no_ref_wraparound_constraint_flag  u (1)   no_temporal_mvp_constraint_flag  u (1)   no_sbtmvp_constraint_flag  u (1)   no_amvr_constraint_flag  u (1)   no_bdof_constraint_flag  u (1)   no_dmvr_constraint_flag  u (1)  

 no_cclm_constraint_flag  u (1)  no_mts_constraint_flag  u (1)  

  no_sbt_constraint_flag  u (1)   no_affine_motion_constraint_flag  u (1)   no_bcw_constraint_flag  u (1)  

 no_ibc_constraint_flag  

  no_ciip_constraint_flag  u (1)   no_fpel_mmvd_constraint_flag  u (1)   no_gpm_constraint_flag  u (1)  

 no_ladf_constraint_flag  u (1)  no_transform_skip_constraint_flag  u (1)  

  no_bdpcm_constraint_flag  u (1)  no_ap_delta_constraint_flag  u (1)  no_dep_quant_constraint_flag  u (1)  no_sign_data_hiding_constraint_flag  u (1)  

  no_mixed_nalu_types_in_pic_constraint_flag  u (1)   no_trail_constraint_flag  u (1)   no_stsa_constraint_flag  u (1)   no_rasl_constraint_flag  u (1)   no_radl_constraint_flag  u (1)  

 no_idr_constraint_flag  u (1)  no_cra_constraint_flag  u (1)  

  no_gdr_constraint_flag  u (1)  no_aps_constraint_flag  u (1)  while( !byte_aligned( ) )   gci_alignment_zero_bit  f (1)  num_reserved_constraint_bytes  u (8)  for i = 0; i < num_reserved_constraint_bytes; i++ )   gci_reserved_constraint_byte[ i ]  u (8) }

6.3.2. Embodiment of Items 4.1 and 4.1b

In one example, the general constraint information semantics are changed as follows:

intra_only_constraint_flag equal to 1 specifies that slice_type shall be equal to 1. intra_only_constraint_flag equal to 0 does not impose such a constraint.

no_transform_skip_constraint_flag equal to 1 specifies that sps_transform_skip_enabled_flag shall be equal to 0. no_transform_skip_constraint_flag equal to 0 does not impose such a constraint.

no_aps_constraint_flag equal to 1 specifies that there shall be no NAL unit with nuh_unit_type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT present in OlsInScope. no_aps_constraint_flag equal to 0 does not impose such a constraint.

6.3.3. Embodiment of Items 4.1 and 4.1c

In one example, the general constraint information semantics are changed as follows:

max_bitdepth_constraint_idc specifies that bit_depth_minus8 shall be in the range of 0 to max_bitdepth_constraint_idc, inclusive.

no_gdr_constraint_flag equal to 1 specifies that there shall be no NAL unit with nuh_unit_type equal to GDR_NUT present in OlsInScope. no_gdr_constraint_flag equal to 0 does not impose such a constraint.

6.4. Fourth Embodiment

This is an embodiment of items 5, and 5.a summarized above in Section 5.

In one example, the syntax structure seq_parameter_set_rbsp( ) is changed as follows:

seq_parameter_set_rbsp( ) { Descriptor  sps_seq_parameter_set_id  u (4) ...  if( !intra_only_constraint_flag )   

 u (1) ...  

  sps_weighted_pred_flag  u (1)   sps_weighted_bipred_flag  u (1)  

...  

  long_term_ref_pics_flag  u (1)

And the syntax structure pic_parameter_set_rbsp( ) is changed as follows:

Descriptor pic_parameter_set_rbsp( ) {  pps_pic_parameter_set_id ue(v)  pps_seq_parameter_set_id u(4)   

 mixed_nalu_types_in_pic_flag u(1)  pic_width_in_lama_samples ue(v)  pic_height_in_luma_samples ue(v) . . .  cabac_init_present_flag u(1)   

  for( i = 0; i < 2; i++ )    num_ref_idx_default_active_minus1[ i ] ue(v)   rpl1_idx_present_flag u(1)   

 init_qp_minus26 se(v)  cu_qp_delta_enabled_flag u(1) . . . And the picture parameter set RBSP semantics are changed as follows: . . .

num_ref_idx_default_active_minus1[i] plus 1, when i is equal to 0, specifies the inferred value of the variable NumRefIdxActive[0] for P or B slices with num_ref_idx_active_override_flag equal to 0, and, when i is equal to 1. specifies the inferred value of NumRefIdxActive[1] for B slices with num_ref_idx_active_override_flag equal to 0. The value of num_ref_idx_default_active_minus1[i] shall be in the range of 0 to 14, inclusive.

rpl1_idx_present_flag equal to 0 specifies that ref_pic_list_sps_flag[1] and ref_pic_list_idx[1] are not present in the PH syntax structures or the slice headers for pictures referring to the PPS. rpl1_idx_present_flag equal to 1 specifies that ref_pic_list_sps_flag[1] and ref_pic_list_idx[1] may be present in the PH syntax structures or the slice headers for pictures referring to the PPS.

. . . And the syntax structure picture_header_structure( ) is changed as follows:

Descriptor picture_header_structure( ) {  gdr_or_irap_pic_flag u(1)  if( gdr_or_irap_pic_flag )   gdr_pic_flag u(1)   

  ph_inter_slice_allowed_flag u(1)  if( ph_inter_slice_allowed_flag )   ph_intra_slice_allowed_flag u(1)  non_reference_picture_flag u(1)  ph_pic_parameter_set_id ue(v)  ph_pic_order_cnt_lsb u(v)  if( gdr_or_irap_pic_flag)   no_output_of_prior_pics_flag u(1) ph_inter_slice_allowed_flag equal to 0 specifies that all coded slices of the picture have slice_type equal to 2. ph_inter_slice_allowed_flag equal to 1 specifies that there may or may not be one or more coded slices in the picture that have slice_type equal to 0 or 1.

And the syntax structure slice_header ( ) is changed as follows:

Descriptor slice_header( ) {  picture_header_in_slice_header_flag u(1)  if( picture_header_in_slice_header_flag )   picture_header_structure( )  if( subpic_info_present_flag )   slice_subpic_id u(v) . . .  if( separate_colour_plane_flag = = 1 )   colour_plane_id u(2)  if(  

  !rpl_info_in_ph_flag && ( ( nal_unit_type != IDR_W_RADL && nal_unit_type !=    IDR_N_LP ) | | sps_idr_rpl_present_flag ) )   ref_pic_lists( )  if(  

  ( rpl_info_in_ph_flag | | ( ( nal_unit_type != IDR_W_RADL && nal_unit_type !=    IDR_N_LP ) | | sps_idr_rpl_present_flag ) ) &&    ( slice_type != I && num_ref_entries[ 0 ][ RplsIdx[ 0 ] ] > 1) | |    (slice_type = = B && num_ref_entries[ 1 ][ RplsIdx[ 1 ] ] > 1 ) ) {   msm_ref_idx_active_override_flag u(1)   if( num_ref_idx_active_override_flag )    for i = 0; i < ( slice type = = B ? 2: 1 ); i++ )     if( num_ref_entries[ i ][ RplsIdx[ i ] ] > 1 )      num_ref_idx_active_minus1[ i ] ue(v)  }

6.5. Fifth Embodiment

This is an embodiment of items 6, and 6.1 summarized above in Section 5. In one example, the syntax structure seq_paranreter_set_rbsp( ) is changed as follows:

Descriptor seq_parameter_set_rbsp( ) {  sps_seq_parameter_set_id u(4)  sps_video_parameter_set_id u(4) . . .  if(  

  sps_entropy_coding_sync_enabled_flag u(1)  if(  

  

sps_entropy_coding_sync_enabled_flag )   sps_wpp_entry_point_offsets_present_flag u(1)   

  sps_weighted_pred_flag u(1)   

  sps_weighted_bipred_flag u(1)  log2_max_pic_order_cnt_lsb_minus4 u(4) . . .   

  long_term_ref_pics_flag u(1)   

  inter_layer_ref_pics_present_flag u(1) . . .   

  

  sps_max_luma_transform_size_64_flag u(1) . . .   

  sps_smvd_enabled_flag u(1) . . .   

  sps_mmvd_esabled_flag u(1)   

  sps_isp_enabled_flag u(1)   

  sps_mrl_enabled_flag u(1)   

  sps_mip_enabled_flag u(1) . . .   

  sps_palette_enabled_flag u(1)  if(  

  ChromaArrayType = = 3 && !sps_max_luma_transform_size_64_flag )   sps_act_enabled_flag u(1) . . .   

  sps_lmcs_enabled_flag u(1)   

  sps_lfnst_enabled_flag u(1) . . .   

  

  log2_parallel_merge_level_minus2 ue(v)   

  sps_scaling_list_enabled_flag u(1) . . .   

  sps_virtual_boundaries_enabled_flag u(1) sps_entropy_coding_sync_enabled_flag equal to 1 specifies that a specific synchronization process for context variables is invoked before decoding the CTU that includes the first CTB of a row of CTBs in each tile in each picture referring to the SPS, and a specific storage process for context variables is invoked after decoding the CTU that includes the first CTB of a row of CTBs in each tile in each picture referring to the SPS. sps_entropy_coding_sync_enabled_flag equal to 0 specifies that no specific synchronization process for context variables is required to be invoked before decoding the CTU that includes the first CTB of a row of CTBs in each tile in each picture referring to the SPS, and no specific storage process for context variables is required to be invoked after decoding the CTU that includes the first CTB of a row of CTBs in each tile in each picture referring to the SPS.

sps_wpp_entry_point_offsets_present_flag equal to 1 specifies that signalling for entry point offsets for CTU rows may be present in the slice headers of pictures referring to the SPS when sps_entropy_coding_sync_enabled_flag is equal to 1. sps_wpp_entry_point_offsets_present_flag equal to 0 specifies that signalling for entry point offsets for CTU rows are not present in the slice headers of pictures referring to the SPS. When not present, the value of sps_wpp_entry_point_offsets_present_flag is inferred to be equal to 0.

sps_weighted_pred_flag equal to 1 specifies that weighted prediction may be applied to P slices referring to the SPS. sps_weighted_pred_flag equal to 0 specifies that weighted prediction is not applied to P slices referring to the SPS.

sps_weighted_bipred_flag equal to 1 specifies that explicit weighted prediction may be applied to B slices referring to the SPS. sps_weighted_bipred_flag equal to 0 specifies that explicit weighted prediction is not applied to B slices referring to the SPS.

long_term_ref_pics_flag equal to 0 specifies that no LTRP is used for inter prediction of any coded picture in the CLVS. long_term_ref_pics_flag equal to 1 specifies that LTRPs may be used for inter prediction of one or more coded pictures in the CLVS.

inter_layer_ref_pics_present_flag equal to 0 specifies that no ILRP is used for inter prediction of any coded picture in the CLVS. inter_layer_ref_pic_flag equal to 1 specifies that ILRPs may be used for inter prediction of one or more coded pictures in the CLVS. When sps_video_parameter_set_id is equal to 0, the value of inter_layer_ref_pics_present_flag is inferred to be equal to 0. When vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1, the value of inter_layer_ref_pics_present_flag shall be equal to 0.

sps_max_luma_transform_size_64_flag equal to 1 specifies that the maximum transform size in luma samples is equal to 64. sps_max_luma_transform_size_64_flag equal to 0 specifies that the maximum transform size in luma samples is equal to 32.

sps_smvd_enabled_flag equal to 1 specifies that symmetric motion vector difference may be used in motion vector decoding. sps_smvd_enabled_flag equal to 0 specifies that symmetric motion vector difference is not used in motion vector coding.

sps_mmvd_enabled_flag equal to 1 specifies that merge mode with motion vector difference is enabled sps_mmvd_enabled_flag equal to 0 specifies that merge mode with motion vector difference is disabled.

sps_isp_enabled_flag equal to 1 specifies that intra prediction with subpartitions is enabled. sps_isp_enabled_flag equal to 0 specifies that intra prediction with subpartitions is disabled.

sps_mrl_enabled_flag equal to 1 specifies that infra prediction with multiple reference lines is enabled. sps_mrl_enabled_flag equal to 0 specifies that intra prediction with multiple reference lines is disabled.

sps_mip_enabled_flag equal to 1 specifies that matrix-based intra prediction is enabled. sps_mip_enabled_flag equal to 0 specifies that matrix-based intra prediction is disabled.

sps_palette_enabled_flag equal to 1 specifies that pred_mode_plt_flag may be present in the coding unit syntax. sps_palette_enabled_flag equal to 0 specifies that pred_mode_plt_flag is not present in the coding unit syntax. When sps_palette_enabled_flag is not present, it is inferred to be equal to 0.

sps_act_enabled_flag equal to 1 specifies that adaptive colour transform may be used and the cu_act_enabled_flag may be present in the coding unit syntax. sps_act_enabled_flag equal to 0 specifies that adaptive colour transform is not used and cu_act_enabled_flag is not present in the coding unit syntax. When sps_act_enabled_flag is not present, it is inferred to be equal to 0.

sps_lmcs_enabled_flag equal to 1 specifies that luma mapping with chroma scaling is used in the CLVS. sps_lmcs_eenabled_flag equal to 0 specifies that luma mapping with chroma scaling is not used in the CLVS.

sps_lfnst_enabled_flag equal to 1 specifies that lfnst_idx may be present in infra coding unit syntax. sps_lfnst_enabled_flag equal to 0 specifies that lfnst_idx is not present in intra coding unit syntax.

log2_parallel_merge_level_minus2 plus 2 specifies the value of the variable Log2ParMrgLevel, which is used in the derivation process for spatial merging candidates as specified in clause 8.5.2.3, the derivation process for motion vectors and reference indices in subblock merge mode as specified in clause 8.5.5.2, and to control the invocation of the updating process for the history-based motion vector predictor list in clause 8.5.2.1. The value of log2_parallel_merge_level_minus2 shall be in the range of 0 to CtbLog2SizeY−2, inclusive. The variable Log2ParMrgLevel is derived as follows:

Log2ParMrgLevel=log2_parallel_merge_level_minus2+2  (68)

sps_scaling_list_enabled_flag equal to 1 specifies that a scaling list is used for the scaling process for transform coefficients sps_scaling_list_enabled_flag equal to 0 specifies that scaling list is not used for the scaling process for transform coefficients.

sps_virtual_boundaries_present_flag equal to 1 specifies that information of virtual boundaries is signalled in the SPS. sps_virtual_boundaries_present_flag equal to 0 specifies that information of virtual boundaries is not signalled in the SPS. When there is one or more than one virtual boundaries signalled in the SPS, the in-loop filtering operations are disabled across the virtual boundaries in pictures referring to the SPS. In-loop filtering operations include the deblocking filter, sample adaptive offset filter, and adaptive loop filter operations.

And the syntax structure general_constraint_info ( ) is changed as follows:

Descriptor general_constraint_info( ) {  general_progressive_source_flag u(1)  general_interlaced_source_flag  general_non_packed_constraint_flag u(1)  general_frame_only_constraint_flag u(1)  general_non_projected_constraint_flag u(1)  intra_only_constraint_flag u(1)  max_bit_depth_constraint_idc u(4)  max_chroma_format_constraint_idc u(2)   

  

 _ 

  

   

   

   

   

   

  

. . .   

 _ 

  

. . .   

  no_ref_wraparound_constraint_flag u(1)   no_temporal_mvp_constraint_flag u(1)   no_sbtmvp_constraint_flag u(1)   no_amvr_constraint_flag u(1)   no_bdof_constraint_flag u(1)    

  no_dmvr_constraint_flag u(1)    

  

  

  

  

  

u(1) . . .   

  

 no_ibc_constraint_flag u(1) . . .   

u(1)   

u(1)  no_ladf_constraint_flag u(1)  no_transform_skip_constraint_flag u(1) . . .  no_qp_delta_constraint_flag u(1)   

  

  

  

 no_dep_quant_constraint_flag u(1)  no_sign_data_hiding_constraint_flag u(1)   

  

  

intra_only_constraint_flag equal to 1 specifies that slice_type shall be equal to 1. intra_only_constraint_flag equal to 0 does not impose such a constraint.

no_entropy_coding_sync_constraint_flag

no_wpp_entry_point_offsets_present_constraint_flag

no_weighted_pred_constraint_flag

no_weighted_bipred_constraint_flag

no_long_term_ref_pics_constraint_flag

6.6. Sixth Embodiment

This is an embodiment of items 7.7.1, 7.2.c and 7.2.d summarized above in Section 5.

6.6.1. Embodiment of Items 7.1 and 7.2.c

In one example, the syntax structure adaptation_parameter_set_rbsp ( ) is changed as follows:

Descriptor adaptation parameter set rbsp( ) {  adaptation_parameter_set_id u(5)   

 aps_params_type u(3)  if( aps_params_type = = ALF_APS )   alf_data( )  else if( aps_params_type = = LMCS_APS )   lmcs_data( )  else if( aps_params_type = = SCALING_APS )   scaling_list_data( )  aps_extension_flag u(1)  if( aps_extension_flag )   while( more_rbsp_data( ) )    aps_extension_data_flag u(1)  rbsp_trailing_bits( ) }

And the semantics of adaptive loop filter data are changed as follows: alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filter is signalled. alf_chroma_filter_signal_flag equal to 0 specifies that a chroma filter is not signalled. When ChromaArrayType is equal to 0, alf_chroma_filter_signal_flag shall be equal to 0.

at least one of the values of alf_luma_filter_signal_flag, alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag and alf_cc_cr_filter_signal_flag shall be equal to 1.

6.6.2. Embodiment of Item 7.2.d

In one example, the semantics of adaptive loop filter data are changed as follows: alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filter is signalled. alf_chroma_filter_signal_flag equal to 0 specifies that a chroma filter is not signalled. When ChromaArrayType is equal to 0, alf_chroma_filter_signal_flag shall be equal to 0.

at least one of the values of alf_luma_filter_signal_flag, alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag and alf_cc_cr_filter_signal_flag shall be equal to 1.

6.7. Seven Embodiment

Below are some example embodiments for some of the invention aspects summarized above in Section 5, which can be applied to the MSC specification. The changed texts are based on the latest VVC text in JVET-Q2001-vE. Most relevant parts that have been added or modified are highlighted in bold and Italic, and some of the deleted parts are marked with double brackets (e.g., [[a]] denotes the deletion of the character “a”).

7.3.2.5 Adaptation Parameter Set RBSP Syntax

Descriptor adaptation_parameter_set_rbsp( ) {  adaptation_parameter_set_id u(5)  aps_params_type u(3)    

 if( aps_params_type = = ALF_APS )   alf_data( )  else if( aps_params_type = = LMCS_APS )   lmcs_data( )  else if( aps_params_type = = SCALING_APS )   scaling_list_data( )  aps_extension_flag u(1)  if( aps_extension_flag)   while( more_rbsp_data( ) )    aps_extension_data_flag u(1)  rbsp_trailing_bits( ) }

7.3.2.19 Adaptive Loop Filter Data Syntax

Descriptor alf_data( ) {  alf_luma_filter_signal_flag u(1)   

  alf_chroma_filter_signal_flag u(1)   alf_cc_cb_filter_signal_flag u(1)   alf_cc_cr_filter_signal_flag u(1)   

. . . 7.3.2.20 Luma Mapping with Chroma Scaling Data Syntax

Descriptor lmcs _data( ) {  lmcs_min_bin_idx ue(v)  lmcs_delta_max_bin_ idx ue(v)  lmcs_delta_cw_prec_minus1 ue(v)  for( i = lmcs_min_bin_idx; i <= LmcsMaxBinIdx; i++ ) {   lmcs_delta_abs_cw[ i ] u(v)   if( lmcs_delta_abs_cw[ i ] > 0 )    lmcs_delta_sign_cw_flag[ i ] u(1)  }   

  lmcs_delta_abs_crs u(3)  if( lmcs_delta_abs_crs > 0 )   lmcs_delta_sign_crs_flag u(1) }

7.3.2.21 Scaling List Data Syntax

Descriptor scaling_list_data( ) {  scaling_matrix_for_lfnst_disabled_flag u(1)  [[scaling_list_chroma_present_flag]]  for( id = 0; id < 28; id ++ )   matrixSize = (id < 2 ) ? 2 : ( ( id < 8 ) ? 4 : 8 )   if( aps_chroma_params_present_flag[[scaling_list_chroma_present_flag]] | | ( id % 3 = = 2 ) | | ( id = = 27 ) ) {    scaling_list_copy_mode_flag[ id ] u(1)    if( !scaling_list_copy_mode_flag[ id ] )     scaling_list_pred_mode_flag[ id ] u(1)    if( ( scaling_list_copy_mode_flag[ id ] | | scaling_list_pred_mode_flag[ id ] ) &&      id != 0 && id != 2 && id != 8 )     scaling_list_pred_id_delta[ id ] ue(v)    if( !scaling_list_copy_mode_flag[ id ] ) {     nextCoef = 0     if( id > 13 ) {      scaling_list_dc_coef[ id − 14 ] se(v)      nextCoef += scaling_list_dC_coef[ id − 14 ]     }     for( i = 0; i < matrixSize * matrixSize; i++ ) {      x = DiagScanOrder[ 3 ] [ 3 ] [ i ] [ 0 ]      y = DiagScanOrder[ 3 ] [ 3 ] [ i ] [ 1 ]      if ( !( id > 25 && x >= 4 && y >= 4 ) ) {       scaling_list_delta_coef[ id ][ i ] se(v)       nextCoef += scaling_list_delta_coef[ id ][ i ]      }      ScalingList[ id ][ i ] = nextCoef     }    }   }  } } And the PH semantics are changed as follows: . . . ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS that the luma component of the slices associated with the PH refers to. The value of alf_luma_filter_signal_flag of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i] shall be equal to 1. The TemporalId of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i] shall be less than or equal to the TemporalId of the picture associated with the PH.

==

. . . ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APS that the slices associated with the PH refers to. The TemporalId of the APS NAL unit having aps_params_type equal to LMCS_APS and adaptation_parameter_set_id equal to ph_lmcs_aps_id shall be less than or equal to the TemporalId of the picture associated with PH.

==

. . . ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of the scaling list APS. The TemporalId of the APS NAL unit having aps_params_type equal to SCALING_APS and adaptation_parameter_set_id equal to ph_scaling_list_aps_id shall be less than or equal to the TemporalId of the picture associated with PH.

==

And the SH semantics are changed as follows: slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS that the luma component of the slice refers to. The TemporalId of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shall be less than or equal to the TemporalId of the coded slice NAL unit. When slice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is not present, the value of slice_alf_aps_id_luma[i] is inferred to be equal to the value of ph_alf_aps_id_luma[i]. The value of alf_luma_filter_signal_flag of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shall be equal to 1.

==0˜0:1. And the ALF data semantics are changed as follows: . . . alf_luma_filter_signal_flag equal to 1 specifies that a luma filter set is signalled. alf_luma_filter_signal_flag equal to 0 specifies that a luma filter set is not signalled. alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filter is signalled. alf_chroma_filter_signal_flag equal to 0 specifies that a chroma filter is not signalled.

[[When ChromaArrayType is equal to 0, alf_chroma_filter_signal_flag shall be equal to 0.]] alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-component filters for the Cb colour component are signalled_alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-component filters for Cb colour component are not signalled.

[[When ChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall be equal to 0.]] alf_cc_cr_filter_signal_flag equal to 1 specifies that cross-component filters for the Cr colour component are signalled. alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-component filters for the Cr colour component are not signalled.

[[When ChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall be equal to 0.]] . . . And the SCALING data semantics are changed as follows: . . . [[scaling_list_chroma_present_flag equal to 1 specifies that chroma scaling lists are present in scaling_list_data( ). scaling_list_chroma_present_flag equal to 0 specifies that chroma scaling lists are not present in scaling_list_data( ). It is a requirement of bitstream conformance that scaling_list_chroma_present_flag shall be equal to 0 when ChromaArrayType is equal to 0, and shall be equal to 1 when ChromaArrayType is not equal to 0.]]

6.8. Eighth Embodiment

Below are some example embodiments for some of the invention aspects summarized above in Section 5, which can be applied to the VVC specification. The changed texts are based on the latest VVC text in JVET-Q2001-vE. Most relevant parts that have been added or modified are bold and Italic, and some of the deleted parts are marked with double brackets (e.g., [[a]] denotes the deletion of the character “a”).

Descriptor adaptation_parameter_set_rbsp( ) {  adaptation_parameter_set_id u(5)  aps_params_type u(3)   

 if_aps_params_type = = ALF_APS )   alf_data( )  else if( aps_params_type = = LMCS_APS )   lmcs_data( )  else if( aps_params_type = = SCALING_APS )   scaling_list_data( )  aps_extension_flag u(1)  if( aps_extension_flag )   while( more_rbsp_data( ) )    aps_extension_data_flag u(1)  rbsp_trailing_bits( ) }

Descriptor alf_data( ) {  alf_luma_filter_signal_flag u(1)   

  alf_chroma_filter_signal_flag u(1)   alf_cc_cb_filter_signal_flag u(1)   alf_cc_cr_filter_signal_flag u(1)   

 . . . }

Descriptor lmcs_data( ) {  . . .   

  lmcs_delta_abs_crs u(3)  . . . }

Descriptor scaling_list_data( ) {  scaling_matrix_for_lfnst_disabled_flag u(1)   [ [ scaling_list_chroma_present_flag] ] [[u(1)]]  for id = 0; id < 28; id ++ )   matrixSize = (id < 2 ) ? 2 : ((id < 8 ) ? 4 : 8 )   if([[scaling_list]]  

 _chroma_present_flag | | ( id % 3 = = 2 ) | | (id = = 27 ) ) {  ... }

7.4.3.1 Picture Header Structure Semantics

ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS that the luma component of the slices associated with the PH refers to

-   -   The value of alf_luma_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i] shall         be equal to 1.     -   The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         ph_alf_aps_id_luma[i] shall be less than or equal to the         TemporalId of the picture associated with the PH.     -            . . .         ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id         of the ALF APS that the chroma component of the slices         associated with the PH refers to     -   The value of alf_chroma_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to ph_alf_aps_id_chroma shall         be equal to 1.     -   The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         ph_alf_aps_id_chroma shall be less than or equal to the         TemporalId of the picture associated with the PH.     -            . . .         ph_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id of         the ALF APS that the Cb colour component of the slices         associated with the PH refers to.     -   The value of alf_cc_cb_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_id shall         be equal to 1.

The TemporalId of the APS NAL unit having aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

-   -            . . .         ph_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id of         the ALF APS that the Cr colour component of the slices         associated with the PH refers to.     -   The value of alf_cc_cr_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to ph_cc_alf_cr_aps_id shall         be equal to 1.     -   The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         ph_cc_alf_cr_aps_id shall be less than or equal to the         TemporalId of the picture associated with the PH.     -            . . .         ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the         LMCS APS that the slices associated with the PH refers to.     -   The TemporalId of the APS NAL unit having aps_params_type equal         to LMCS_APS and adaptation_parameter_set_id equal to         ph_lmcs_aps_id shall be less than or equal to the TemporalId of         the picture associated with PH.     -   ==         . . .         ph_scaling_list_aps_id specifies the adaptation_parameter_set_id         of the scaling list APS.     -   The TemporalId of the APS NAL unit having aps_params_type equal         to SCALING_APS and adaptation_parameter_set_id equal to         ph_scaling_list_aps_id shall be less than or equal to the         TemporalId of the picture associated with PH.     -   ==

7.3.7.1 General Slice Header Semantics

. . . slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS that the luma component of the slice refers to. When slice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is not present, the value of slice_alf_aps_id_luma[i] is inferred to be equal to the value of ph_alf_aps_id_luma[i].

-   -   The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         slice_alf_aps_id_luma[i] shall be less than or equal to the         TemporalId of the coded slice NAL unit.     -   The value of alf_luma_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF APS and         adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i]         shall be equal to 1.     -            . . .         slice_alf_aps_id_chroma specifies the         adaptation_parameter_set_id of the ALF APS that the chroma         component of the slice refers to. When slice_alf_enabled_flag is         equal to 1 and slice_alf_aps_id_chroma is not present, the value         of slice_alf_aps_id_chroma is inferred to be equal to the value         of ph_alf_aps_id_chroma.     -   The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         slice_alf_aps_id_chroma shall be less than or equal to the         TemporalId of the coded slice NAL unit.     -   The value of alf_chroma_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to slice_alf_aps_id_chroma         shall be equal to 1.     -            . . .         slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id         that the Cb colour component of the slice refers to. When         slice_cc_alf_cb_enabled_flag is equal to 1 and         slice_cc_alf_cb_aps_id is not present, the value of         slice_cc_alf_cb_aps_id is inferred to be equal to the value of         ph_cc_alf_cb_aps_id.     -   The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         slice_cc_alf_cb_aps_id shall be less than or equal to the         TemporalId of the coded slice NAL unit.     -   The value of alf_cc_cb_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to slice_cc_alf_cd_aps_id         shall be equal to 1.     -            . . .         slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id         that the Cr colour component of the slice refers to. When         slice_cc_alf_cr_enabled_flag is equal to 1 and         slice_cc_alf_cr_aps_id is not present, the value of         slice_cc_alf_cr_aps_id is inferred to be equal to the value of         ph_cc_alf_cr_aps_id.     -   The TemporalId of the APS NAL unit having aps_params_type equal         to ALF_APS and adaptation_parameter_set_id equal to         slice_cc_alf_cr_aps_id shall be less than or equal to the         TemporalId of the coded slice NAL unit.     -   The value of alf_cc_cr_filter_signal_flag of the APS NAL unit         having aps_params_type equal to ALF_APS and         adaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id         shall be equal to 1.     -            . . .

7.4.3.19 Adaptive Loop Filter Data Semantics

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filter is signalled. alf_chroma_filter_signal_flag equal to 0 specifies that a chroma filter is not signalled. When [[ChromaArrayType is equal to 0]]

alf_chroma_filter_signal_flag

[[shall]] be equal to 0. . . . alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-component filters for the Cb colour component are signalled. alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-component filters for Cb colour component are not signalled. When [[ChromaArrayType is equal to 0]]

alf_cc_cb_filter_signal_flag

[[shall]] be equal to 0. alf_cc_cr_filter_signal_flag equal to 1 specifies that cross-component filters for the Cr colour component are signalled. alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-component filters for the Cr colour component are not signalled. When [[ChromaArrayType is equal to 0]]

alf_cc_cr_filter_signal_flag

[[shall]] be equal to 0.

7.4.3.21 Scaling List Data Semantics

[[scaling_list]]

_chroma_present_flag equal to 1 specifies that chroma

scaling lists are present

scaling_list_data( ). [[scaling_list]]

_chroma_present_flag equal to 0 specifies that chroma

scaling lists are not present respectively in all data, lmcs_data and scaling_list_data( ). [[It is a requirement of bitstream conformance that scaling_list_chroma_present_flag shall be equal to 0 when ChromaArrayType is equal to 0, and shall be equal to 1 when ChromaArrayType is not equal to 0.]]

6.1. Ninth Embodiment

Below are some example embodiments for some of the invention aspects summarized above in Section 5, which am be applied to the specification. The changed texts are based on the latest VVC text in JVET-R2001-vA. Most relevant parts that have been added or modified are highlighted in bold and Italic, and some of the deleted parts are marked with double brackets (e.g., [[a]] denotes the deletion of the character “a”).

7.3.3 Profile, Tier, and Level Syntax 7.3.3.1 General Profile, Tier, and Level Syntax

Descriptor profile_tier_level( profileTierPresentFlag, maxNumSubLayersMinus1 ) {  if( profileTierPresentFlag ) {   general_profile_idc u(7)   general_tier_flag u(1)    

   

   general_constraint_info( )    

    

 }  general_level_idc u(8)  if( profileTierPresentFlag ) {   ptl_num_sub_profiles u(8)   for( i = 0; i < ptl_num_sub_profiles; i++ )    general_sub_profile_idc[ i ] u(32)  }  for( i = 0; i < maxNumSubLayersMinus1; i++ )   ptl_sublayer_level_present_flag[ i ] u(1)  while( !byte_aligned( ))   ptl_alignment_zero_bit f(1)  for i = 0; i < maxNumSubLayersMinus1; i++ )   if( ptl_sublayer_level_present_flag[ i ] )    sublayer_level_idc[ i ] u(8) } . . .

. . .

7.3.3.2 General Constraint Information Syntax

Descriptor general_constraint_info( ) {  general_non_packed_constraint_flag u(1)  general_frame_only_constraint_flag u(1)  general_non_projected_constraint_flag u(1)  general_one_picture_only_constraint_flag u(1)  intra_only_constraint_flag u(1)  max_bitdepth_constraint_idc u(4)  max_chroma_format_constraint_idc u(2)  single_layer_constraint_flag u(1)  all_layers_independent_constraint_flag u(1)  no_ref_pic_resampling_constraint_flag u(1)  no_res_change_in_clvs_constraint_flag u(1)  one_tile_per_pic_constraint_flag u(1)  pic_header_in_slice_header_constraint_flag u(1)  one_slice_per_pic_constraint_flag u(1)  one_subpic_per_pic_constraint_flag u(1)  no_qtbtt_dual_tree_intra_constraint_flag u(1)  no_partition_constraints_override_constraint_flag u(1)  no_sao_constraint_flag u(1)  no_alf_constraint_flag u(1)  no_ccalf_constraint_flag u(1)  no_joint_cbcr_constraint_flag u(1)  no_mrl_constraint_flag u(1)  no_isp_constraint_flag u(1)  no_mip_constraint_flag u(1)   

  

  

  

 no_ref_wraparound_constraint_flag u(1)  no_temporal_mvp_constraint_flag u(1)  no_sbtmvp_constraint_flag u(1)  no_amvr_constraint_flag u(1)  no_bdof_constraist_flag u(1)  no_dmvr_constraint_flag u(1)  no_cclm_constraint_flag u(1)  no_mts_constraint_flag u(1)  no_sbt_constraint_flag u(1)  no_lfnst_constraint_flag u(1)   

  

 no_affine_motion_constraint_flag u(1)  no_mmvd_constraint_flag u(1)  no_smvd_constraint_flag u(1)  no_prof_constraint_flag u(1)  no_bcw_constraint_flag u(1)  no_ibc_constraint_flag u(1)  no_ciip_constraint_flag u(1)  no_gpm_constraint_flag u(1)  no_ladf_constraint_flag u(1)  no_transform_skip_constraint_flag u(1)  no_bdpcm_constraint_flag u(1)  no_palette_constraint_flag u(1)  no_act_constraint_flag u(1)  no_lmcs_constraint_flag u(1)  no_cu_qp_delta_constraint_flag u(1)  no_chroma_qp_offset_constraint_flag u(1)  no_dep_quant_constraint_flag u(1)  no_sign_data_hiding_constraint_flag u(1)   

  

 no_tsrc_constraint_flag u(1)  no_mixed_nalu_types_in_pic_constraint_flag u(1)  no_trail_constraint_flag u(1)  no_stsa_constraint_flag u(1)  no_rasl_constraint_flag u(1)  no_radl_constraint_flag u(1)  no_idr_constraint_flag u(1)  no_cra_constraint_flag u(1)  no_gdr_constraint_flag u(1)  no_aps_constraint_flag u(1) [[ while( !byte_aligned( ) )]]   [[gci_alignment_zero_bit]] [[f(1)]  gci_num_reserved_b[[ytes]] 

u([[8]] 

 )  for( i = 0; i < gci_num_reserved_b[[ytes]] 

 ; i++ )   gci_reserved_b[[yte]] 

  [ i ] u([[8]] 

 ) } 7.4.4.2 General constraint information semantics . . . intra_only_constraint_flag equal to 1 specifies that sp_slice_type shall be equal to 1

intra_only_constraint_flag equal to 0 does not impose such a constraint. to 1.

max_bitdepth_constraint_idc specifies that sps_bit_depth_minus8 shall be in the range of 0 to max_bitdepth_constraint_idc, inclusive.

max_chroma_format_constraint_idc specifies that sps_chroma_format_idc shall be in the range of 0 to max_chroma_format_constraint_idc, inclusive. single_layer_constraint_flag equal to 1 specifies that sps_video_parameter_set_id shall be equal to 0. single_layer_constraint_flag equal to 0 does not impose such a constraint. When general_one_picture_only_constraint_flag is equal to 1, the value of single_layer_constraint_flag shall be equal to 1. all_layers_independent_constraint_flag equal to 1 specifies that vps_all_independent_layers_flag shall be equal to 1. all_layers_independent_constraint_flag equal to 0 does not impose such a constraint.

no_ref_pic_resampling_constraint_flag equal to 1 specifies that sps_ref_pic_resampling_enabled_flag shall be equal to 0. no_ref_pic_resampling_constraint_flag equal to 0 does not impose such a constraint.

no_res_change_in_clvs_constraint_flag equal to 1 specifies that sps_res_change_in_clvs_allowed_flag shall be equal to 0. no_res_change_in_clvs_constraint_flag equal to 0 does not impose such a constraint.

one_tile_per_pic_constraint_flag equal to 1 specifies that each picture shall contain only one tile, i.e., the value of

one_tile_per_pic_constraint_flag equal to 0 does not impose such a constraint.

pic_header_in_slice_header_constraint_flag equal to 1 specifies that each picture shall contain only one slice and the value of sh_picture_header_in_slice_header_flag in each slice shall be equal to 1. pic_header_in_slice_header_constraint_flag equal to 0 does not impose such a constraint. one_slice_per_pic_constraint_flag equal to 1 specifies that each picture shall contain only one slice,

one_slice_per_pic_constraint_flag equal to 0 does not impose such a constraint.

When pic_header_in_slice_header_constraint_flag is equal to 1, the value of one_slice_per_pic_constraint_flag shall be equal to 1. one_subpic_per_pic_constraint_flag equal to 1 specifies the [[each picture shall contain only one subpicture]]

one_subpic_per_pic_constraint_flag equal to 0 does not impose such a constraint. When one_slice_per_pic_constraint_flag is equal to 1, the value of one_subpic_per_pic_constraint_flag shall be equal to 1. . . .

. . . no_sbt_constraint_flag equal to 1 specifies that sps_sbt_enabled_flag shall be equal to 0. no_sbt_constraint_flag equal to 0 does not impose such a constraint.

. . . no_transform_skip_constraint_flag equal to 1 specifies that sps_transform_skip_enabled_flag shall be equal to 0. no_transform_skip_constraint_flag equal to 0 does not impose such a constraint. no_bdpcm_constraint_flag equal to 1 specifies that sps_bdpcm_enabled_flag shall be equal to 0. no_bdpcm_constraint_flag equal to 0 does not impose such a constraint.

no_palette_constraint_flag equal to 1 specifies that sps_palette_enabled_flag shall be equal to 0. no_palette_constraint_flag equal to 0 does not impose such a constraint. no_act_constraint_flag equal to 1 specifies that sps_act_enabled_flag shall be equal to 0. no_act_constraint_flag equal to 0 does not impose such a constraint. no_lmcs_constraint_flag equal to 1 specifies that sps_lmcs_enabled_flag shall be equal to 0. no_lmcs_constraint_flag equal to 0 does not impose such a constraint.

no_cu_qp_delta_constraint_flag equal to 1 specifies that pps_cu_qp_delta_enabled_flag shall be equal to 0. no_cu_qp_delta_constraint_flag equal to 0 does not impose such a constraint. no_chroma_qp_offset_constraint_flag equal to 1 specifies that pps_cu_chroma_qp_offset_list_enabled_flag shall be equal to 0. no_chroma_qp_offset_constraint_flag equal to 0 does not impose such a constraint. no_dep_quant_constraint_flag equal to 1 specifies that sps_dep_quant_enabled_flag shall be equal to 0. no_dep_quant_constraint_flag equal to 0 does not impose such a constraint. no_sign_data_hiding_constraint_flag equal to 1 specifies that sps_sign_data_hiding_enabled_flag shall be equal to 0. no_sign_data_hiding_constraint_flag equal to 0 does not impose such a constraint.

. . . no_idr_constraint_flag equal to 1 specifies that there shall be no NAL unit with nuh_unit_type equal to IDR_W_RADL or IDR_N_LP present in OlsInScope. no_idr_constraint_flag equal to 0 does not impose such a constraint. no_cra_constraint_flag equal to 1 specifies that there shall be no NAL unit with nuh_unit_type equal to CRA_NUT present in OlsInScope. no_cra_constraint_flag equal to 0 does not impose such a constraint.

no_gdr_constraint_flag equal to 1 specifies that sps_gdr_enabled_flag shall be equal to 0. no_gdr_constraint_flag equal to 0 does not impose such a constraint.

no_aps_constraint_flag equal to 1 specifies that there shall be no NAL unit with nuh_unit_type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT present in OlsInScope, and sps_lmcs_enabled_flag, sps_explicit_scaling_list_enabled_flag.

shall [[both]]

[[gci_alignment_zero_bits shall be equal to 0.]] gci_num_reserved_b[[ytes]]

specifies the number of the reserved constraint b[[ytes]]its. The value of gci_num_teserved_b[[ytes]]

shall be 0. Other values of gci_num_reserved_b[[ytes]]its are reserved for future use by ITU-T|ISO/IEC and shall not be present in bitstreams conforming to this version of this Specification. gci_reserved_b[[yte]]

[i] may have any value. Its presence and value do not affect decoder conformance to profiles specified in this version of this Specification. Decoders conforming to this version of this Specification shall ignore the values of all the gci_reserved_b[[yte]]it[i] syntax elements.

FIG. 1 is a block diagram showing an example video processing system 1900 in which various techniques disclosed herein may be implemented. Various implementations may include some or all of the components of the system 1900. The system 1900 may include input 1902 for receiving video content. The video content may be received in a raw or uncompressed format, e.g., 8 or 10 bit multi-component pixel values, or may be in a compressed or encoded format. The input 1902 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interface include wired interfaces such as Ethernet, passive optical network (PON), etc, and wireless interfaces such as Wi-Fi or cellular interfaces.

The system 1900 may include a coding component 1904 that may implement the various coding or encoding methods described in the present document. The coding component 1904 may reduce the average bitrate of video from the input 1902 to the output of the coding component 1904 to produce a coded representation of the video. The coding techniques are therefore sometimes called video compression or video transcoding techniques. The output of the coding component 1904 may be either stored, or transmitted via a communication connected, as represented by the component 1906. The stored or communicated bitstream (or coded) representation of the video received at the input 1902 may be used by the component 1908 for generating pixel values or displayable video that is sent to a display interface 1910. The process of generating user-viewable video from the bitstream representation is sometimes called video decompression. Furthermore, while certain video processing operations are referred to as “coding” operations or tools, it will be appreciated that the coding tools or operations are used at an encoder and corresponding decoding tools or operations that reverse the results of the coding will be performed by a decoder.

Examples of a peripheral bus interface or a display interface may include universal serial bus (USB) or high definition multimedia interface (HDMI) or Displayport, and so on. Examples of storage interfaces include SATA (serial advanced technology attachment), PCI, IDE interface, and the like. The techniques described in the present document may be embodied in various electronic devices such as mobile phones, laptops, smartphones or other devices that are capable of performing digital data processing and/or video display.

FIG. 2 is a block diagram of a video processing apparatus 3600. The apparatus 3600 may be used to implement one or more of the methods described herein. The apparatus 3600 may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on. The apparatus 3600 may include one or more processors 3602, one or more memories 3604 and video processing hardware 3606. The processor(s) 3602 may be configured to implement one or more methods described in the present document. The memory (memories) 3604 may be used for storing data and code used for implementing the methods and techniques described herein. The video processing hardware 3606 may be used to implement, in hardware circuitry, some techniques described in the present document.

FIG. 4 is a block diagram that illustrates an example video coding system 100 that may utilize the techniques of this disclosure.

As shown in FIG. 4 , video coding system 100 may include a source device 110 and a destination device 120. Source device 110 generates encoded video data which may be referred to as a video encoding device. Destination device 120 may decode the encoded video data generated by source device 110 which may be referred to as a video decoding device.

Source device 110 may include a video source 112, a video encoder 114, and an input/output (I/O) interface 116.

Video source 112 may include a source such as a video capture device, an interface to receive video data from a video content provider, and/or a computer graphics system for generating video data, or a combination of such sources. The video data may comprise one or more pictures. Video encoder 114 encodes the video data from video source 112 to generate a bitstream. The bitstream may include a sequence of bits that form a coded representation of the video data. The bitstream may include coded pictures and associated data. The coded picture is a coded representation of a picture. The associated data may include sequence parameter sets, picture parameter sets, and other syntax structures. I/O interface 116 may include a modulator/demodulator (modem) and/or a transmitter. The encoded video data may be transmitted directly to destination device 120 via I/O interface 116 through network 130 a. The encoded video data may also be stored onto a storage medium/server 130 b for access by destination device 120.

Destination device 120 may include an I/O interface 126, a video decoder 124, and a display device 122.

I/O interface 126 may include a receiver and/or a modem. I/O interface 126 may acquire encoded video data from the source device 110 or the storage medium/server 130 b. Video decoder 124 may decode the encoded video data. Display device 122 may display the decoded video data to a user. Display device 122 may be integrated with the destination device 120, or may be external to destination device 120 which be configured to interface with an external display device.

Video encoder 114 and video decoder 124 may operate according to a video compression standard, such as the High Efficiency Video Coding (HEVC) standard, Versatile Video Coding (VVC) standard and other current and/or further standards.

FIG. 5 is a block diagram illustrating an example of video encoder 200, which may be video encoder 114 in the system 100 illustrated in FIG. 4 .

Video encoder 200 may be configured to perform any or all of the techniques of this disclosure. In the example of FIG. 5 , video encoder 200 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of video encoder 200. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

The functional components of video encoder 200 may include a partition unit 201, a predication unit 202 which may include a mode select unit 203, a motion estimation unit 204, a motion compensation unit 205 and an intra prediction unit 206, a residual generation unit 207, a transform unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transform unit 211, a reconstruction unit 212, a buffer 213, and an entropy encoding unit 214.

In other examples, video encoder 200 may include more, fewer, or different functional components. In an example, predication unit 202 may include an intra block copy (IBC) unit. The IBC unit may perform predication in an IBC mode in which at least one reference picture is a picture where the current video block is located.

Furthermore, some components, such as motion estimation unit 204 and motion compensation unit 205 may be highly integrated, but are represented in the example of FIG. 5 separately for purposes of explanation.

Partition unit 201 may partition a picture into one or more video blocks. Video encoder 200 and video decoder 300 may support various video block sizes.

Mode select unit 203 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra- or inter-coded block to a residual generation unit 207 to generate residual block data and to a reconstruction unit 212 to reconstruct the encoded block for use as a reference picture. In some example, Mode select unit 203 may select a combination of intra and inter predication (CIIP) mode in which the predication is based on an inter predication signal and an intra predication signal. Mode select unit 203 may also select a resolution for a motion vector (e.g., a sub-pixel or integer pixel precision) for the block in the case of inter-predication.

To perform inter prediction on a current video block, motion estimation unit 204 may generate motion information for the current video block by comparing one or more reference frames from buffer 213 to the current video block. Motion compensation unit 205 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer 213 other than the picture associated with the current video block.

Motion estimation unit 204 and motion compensation unit 205 may perform different operations for a current video block, for example, depending on whether the current video block is in an I slice, a P slice, or a B slice.

In some examples, motion estimation unit 204 may perform uni-directional prediction for the current video block, and motion estimation unit 204 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. Motion estimation unit 204 may then generate a reference index that indicates the reference picture in list 0 or list 1 that contains the reference video block and a motion vector that indicates a spatial displacement between the current video block and the reference video block. Motion estimation unit 204 may output the reference index, a prediction direction indicator, and the motion vector as the motion information of the current video block. Motion compensation unit 205 may generate the predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.

In other examples, motion estimation unit 204 may perform bi-directional prediction for the current video block, motion estimation unit 204 may search the reference pictures in list 0 for a reference video block for the current video block and may also search the reference pictures in list 1 for another reference video block for the current video block. Motion estimation unit 204 may then generate reference indexes that indicate the reference pictures in list 0 and list 1 containing the reference video blocks and motion vectors that indicate spatial displacements between the reference video blocks and the current video block. Motion estimation unit 204 may output the reference indexes and the motion vectors of the current video block as the motion information of the current video block. Motion compensation unit 205 may generate the predicted video block of the current video block based on the reference video blocks indicated by the motion information of the current video block.

In some examples, motion estimation unit 204 may output a full set of motion information for decoding processing of a decoder.

In some examples, motion estimation unit 204 may do not output a full set of motion information for the current video. Rather, motion estimation unit 204 may signal the motion information of the current video block with reference to the motion information of another video block. For example, motion estimation unit 204 may determine that the motion information of the current video block is sufficiently similar to the motion information of a neighboring video block.

In one example, motion estimation unit 204 may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder 300 that the current video block has the same motion information as the another video block.

In another example, motion estimation unit 204 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD). The motion vector difference indicates a difference between the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 300 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

As discussed above, video encoder 200 may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by video encoder 200 include advanced motion vector predication (AMVP) and merge mode signaling.

Intra prediction unit 206 may perform intra prediction on the current video block. When intra prediction unit 206 performs intra prediction on the current video block, intra prediction unit 206 may generate prediction data for the current video block based on decoded samples of other video blocks in the same picture. The prediction data for the current video block may include a predicted video block and various syntax elements.

Residual generation unit 207 may generate residual data for the current video block by subtracting (e.g., indicated by the minus sign) the predicted video block(s) of the current video block from the current video block. The residual data of the current video block may include residual video blocks that correspond to different sample components of the samples in the current video block.

In other examples, there may be no residual data for the current video block for the current video block, for example in a skip mode, and residual generation unit 207 may not perform the subtracting operation.

Transform processing unit 208 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to a residual video block associated with the current video block.

After transform processing unit 208 generates a transform coefficient video block associated with the current video block, quantization unit 209 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.

Inverse quantization unit 210 and inverse transform unit 211 may apply inverse quantization and inverse transforms to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block. Reconstruction unit 212 may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the predication unit 202 to produce a reconstructed video block associated with the current block for storage in the buffer 213.

After reconstruction unit 212 reconstructs the video block, loop filtering operation may be performed reduce video blocking artifacts in the video block.

Entropy encoding unit 214 may receive data from other functional components of the video encoder 200. When entropy encoding unit 214 receives the data, entropy encoding unit 214 may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.

FIG. 6 is a block diagram illustrating an example of video decoder 300 which may be video decoder 114 in the system 100 illustrated in FIG. 4 .

The video decoder 300 may be configured to perform any or all of the techniques of this disclosure. In the example of FIG. 6 , the video decoder 300 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of the video decoder 300. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

In the example of FIG. 6 , video decoder 300 includes an entropy decoding unit 301, a motion compensation unit 302, an intra prediction unit 303, an inverse quantization unit 304, an inverse transformation unit 305, and a reconstruction unit 306 and a buffer 307. Video decoder 300 may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder 200 (FIG. 5 ).

Entropy decoding unit 301 may retrieve an encoded bitstream. The encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data). Entropy decoding unit 301 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 302 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 302 may, for example, determine such information by performing the AMVP and merge mode.

Motion compensation unit 302 may produce motion compensated blocks, possibly performing interpolation based on interpolation filters. Identifiers for interpolation filters to be used with sub-pixel precision may be included in the syntax elements.

Motion compensation unit 302 may use interpolation filters as used by video encoder 200 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit 302 may determine the interpolation filters used by video encoder 200 according to received syntax information and use the interpolation filters to produce predictive blocks.

Motion compensation unit 302 may uses some of the syntax information to determine sizes of blocks used to encode frame(s) and/or slice(s) of the encoded video sequence, partition information that describes how each macroblock of a picture of the encoded video sequence is partitioned, modes indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter-encoded block, and other information to decode the encoded video sequence.

Intra prediction unit 303 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks. Inverse quantization unit 303 inverse quantizes, i.e., de-quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 301. Inverse transform unit 303 applies an inverse transform.

Reconstruction unit 306 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 202 or intra-prediction unit 303 to form decoded blocks. If desired, a deblocking filter may also be applied to filter the decoded blocks in order to remove blockiness artifacts. The decoded video blocks are then stored in buffer 307, which provides reference blocks for subsequent motion compensation/intra predication and also produces decoded video for presentation on a display device.

A listing of solutions describe some embodiments of the disclosed technology.

A first set of solutions is provided next. The following solutions show example embodiments of techniques discussed in the previous section (e.g., item 1).

1. A video processing method (e.g., method 300 depicted in FIG. 3 ), comprising: performing (302) a conversion between a video having one or more pictures and a coded representation of the video, wherein each of the one or more pictures comprise exactly one slice; wherein the coded representation conforms to a format rule; wherein the format rule specifies that a first field in the coded representation indicative of a profile, a tier and a level that the coded representation conforms to, includes a second field indicative of whether a syntax structure that signals various constraints observed during the conversion is present in the first field.

2. The method of solution 1, wherein the syntax structure comprises a general_constraint_info( ) syntax structure.

3. The method of any of solutions 1-2, wherein the first field comprises Profile Tier Level (PTL) syntax structure.

4. The method of any of solutions 1-3, wherein the second field is a single bit flag.

The following solutions show example embodiments of techniques discussed in the previous section (e.g., item 2).

5. A method of video processing, comprising: performing a conversion between a video comprising one or more pictures and one or more slices and a coded representation of the video, wherein the coded representation conforms to a format rule, wherein the format rule specifies that values of one or more constraint flags at a first level in the coded representation control occurrence of one or more syntax elements at a sequence parameter set (SPS) level or a picture header (PH) level of a slice header (SH) level.

6. The method of solution 5, wherein the format rule specifies to include a syntax element at the SPS level if and only if max_chroma_format_constraint_idc is not equal to a specific value at the first level.

7. The method of solution 6, wherein the syntax element at SPS level comprises a chroma format IDC syntax element.

8. The method of solution 5, wherein the format rule specifies to include a syntax element at the PH level if and only if a general constraint flag is set for a specific value.

9. The method of solution 5, wherein the format rule specifies to include a syntax element at the SH level if and only if a general constraint flag is set for a specific value.

The following solutions show example embodiments of techniques discussed in the previous section (e.g., item 3).

10. A method of video processing, comprising: performing a conversion between a video comprising one or more pictures and one or more slices and a coded representation of the video, wherein the coded representation conforms to a format rule, wherein the format rule specifies that values of one or more constraint flags at a first level in the coded representation constrain values of one or more syntax elements at picture parameter set (PPS) level.

11. The method of solution 10, wherein the one or more constraint flags at the first level include a flag indicating presence of a single tile per picture, and wherein the format rule specifies that fields indicating number of tile rows and number of tile columns have a zero value at the PPS level.

The following solutions show example embodiments of techniques discussed in the previous section (e.g., item 4).

12. The method of any of previous or subsequent solutions, wherein a first syntax portion in the first field controls values and/or occurrence of a second syntax portion in the first field.

13. The method of solution 12, wherein the second syntax portion occurs in the first field if and only if the first syntax portion indicates prespecified values.

14. The method of solution 13, wherein the first syntax portion comprises one_slice_per_pic_constraint_flag and wherein format rule specifies that one_subpic_per_pic_constraint_flag is omitted from the coded representation when one_subpic_per_pic_constraint_flag is equal to zero.

The following solutions show example embodiments of techniques discussed in the previous section (e.g., item 7).

15. A method of video processing, comprising: performing a conversion between a video comprising one or more pictures and one or more slices and a coded representation of the video, wherein the coded representation conforms to a format rule that specifies that the coded representation includes an adaptation_parameter_set that includes syntax elements for identifiers of a video parameter set and/or a sequence parameter set and/or a picture parameter set.

16. The method of solution 15, wherein the format rule specifies that one or more constraint flags control values and/or occurrence of one or more syntax elements in the adaptation_parameter_set.

17. The method of solution 16, the one or more syntax elements in the adaptation parameter set include one or more of alf_luma_filter_signal_flag, alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag or alf_cc_cr_filter_signal_flag.

18. The method of solution 16, wherein the one or more constraint flags are includes in a sequence parameter set or a picture parameter set that is identified by a corresponding identifier.

The following solutions show example embodiments of techniques discussed in the previous section (e.g., item 8).

19. A method of video processing, comprising: performing a conversion between a video comprising one or more pictures and one or more slices and a coded representation of the video, wherein the coded representation conforms to a format rule that specifies to include one or more general constraint flags applicable to the conversion; wherein the one or more general constraint flags are indicative of applicability of general constrain info included in the coded representation to the conversion.

20. The method of solution 19, wherein the applicability of general constraint info is indicated for profiles, levels or tiers for which the general constraint info is applicable.

21. The method of solution 19, wherein the format rule specifies that the general constraint info is includes in a sequence parameter set.

22. The method of solution 1 wherein the format rule specifies that the general constraint info is included in a video parameter set.

The following solutions show example embodiments of techniques discussed in the previous section (e.g., item 9).

23. A method of video processing, comprising. performing a conversion between a video and a coded representation of the video, wherein the coded representation conforms to a format rule, wherein the format rule specifies that the coded representation conditionally includes a general constraint structure carrying general constraint information based on a characteristic of the video or the conversion.

24. The method of solution 23, wherein the characteristic of the video or the conversion comprises a profile or a level or a tier or a sub-profile used for the conversion.

25. The method of solutions 23-24, wherein the format rule specifies that the general constraint structure is included in a profile tier level syntax structure to which the general constraint information is applicable.

26. The method of any of solutions 23-25, wherein the general constraint information indicates a relationship between at least some coding tools and corresponding profiles or levels to which the coding tools are applicable.

27. The method of any of solutions 23-26, wherein the format rule specifies to omit the general constraint structure for a specific profile and/or a specific sub-profile and/or a specific level and/or a specific tier.

28. The method of any of solutions 23-27, wherein the format rule specifies to set an intra only constrain flag to 1 due to all-intra coding being used in a profile or a sub-profile.

29. A video processing method, comprising: performing a conversion between a video and a coded representation of the video, wherein the coded representation conforms to a format rule, wherein the format rule specifies to include a first syntax element that indicates whether one or more second syntax elements are includes in a profile, tier, level information field in the coded representation or a general constraints field in the coded representation.

30. The method of solution 29, wherein the first syntax element signals that the one or more second syntax elements are not included in the coded representation.

31. A video processing method, comprising: performing a conversion between a video and a coded representation of the video, wherein the coded representation conforms to a format rule, wherein the format rule specifies that a syntax field indicative of general constraints is selectively included in the coded representation depending on a profile or a level used for the conversion.

32. The method of solution 31, wherein the format rule further specifies that allowed values of the syntax field are constrained by the profile or the level.

33. The method of any of solutions 1 to 32, wherein the conversion comprises encoding the video into the coded representation.

34. The method of any of solutions 1 to 32, wherein the conversion comprises decoding the coded representation to generate pixel values of the video.

35. A video decoding apparatus comprising a processor configured to implement a method recited in one or more of solutions 1 to 34.

36. A video encoding apparatus comprising a processor configured to implement a method recited in one or more of solutions 1 to 34.

37. A computer program product having computer code stored thereon, the code, when executed by a processor, causes the processor to implement a method recited in any of solutions 1 to 34.

38. A method, apparatus or system described in the present document.

A second set of solutions show example embodiments of techniques discussed in the previous section (e.g., items 14a).

1. A method of video processing (e.g., method 700 as shown in FIG. 7 ), comprising: performing 702 a conversion between a video and a bitstream of the video according to a rule, and wherein the rule specifies that a syntax element is included in a profile, tier, level information syntax structure to indicate whether one or more general constraint information syntax elements are included in a general constraint information syntax structure and/or whether the general constraint information syntax structure is included in the profile, tier, level information syntax structure.

2. The method of solution 1, wherein whether the one or more general constraint information syntax elements are present or not are conditioned on a value of the syntax element.

3. The method of solution 1, wherein the rule specifies that in responsive to the syntax element specifying that general constraint information is not present, the general constraint information syntax structure is not included in the profile, tier, level information syntax structure.

4. The method of solution 3, wherein a value of the syntax element specifying that general constraint information is not present is equal to 0.

5. The method of solution 1, wherein the rule specifies that each of the one or more general constraint information syntax elements is inferred to be a value such that a corresponding constraint is not imposed, in case that the general constraint information syntax structure is not present in the profile, tier, level syntax structure, or that the one or more general constraint information syntax elements are not present in the general constraint information syntax structure.

6. The method of solution 5, wherein the value is 0.

7. The method of solution 1, wherein the rule specifies to infer a value of a first general constraint information syntax element that specifies a requirement of bitstream conformance on a maximum bitdepth indication of samples to be equal to 8 in case that the syntax element has a particular value for the profile, tier, level information syntax structure that is present.

8. The method of solution 7, wherein the rule specifies to infer a value of a second general constraint information syntax element that specifies a requirement of bitstream conformance on a maximum chroma format indication to be equal to 3 in case that the syntax element has a particular value for the profile, tier, level information syntax structure that is present.

9. The method of solution 8, wherein the rule specifies to infer a value of some general constraint information syntax elements to be equal to 0 in case that the syntax element has a particular value for the profile, tier, level information syntax structure that is present.

10. The method of solution 9, wherein the some general constraint information syntax elements are syntax elements included in the general constraint information syntax structure except the first general constraint information syntax element and the second general constraint information syntax element.

11. The method of solution 10, wherein the some general constraint information syntax elements are included in the general constraint information syntax structure such that the some general constraint information syntax elements are from a third general constraint information syntax element specifying a presence of frame packing arrangement SEI messages, segmented rectangular frame packing arrangement SEI messages, equirectangular projection SEI messages, or cubemap projection SEI messages to a fourth general constraint information syntax element specifying a requirement of bitstream conformance on no network abstraction layer (NAL) unit of NAL unit type APS_NUT present in the bitstream.

12. The method of solution 1, wherein the mile further specifies to infer a value of a general constraint information syntax element to be a default value, in case that the constraint information syntax element is not present.

13. The method of solution 12, wherein the default value is 0 or 1.

14. The method of solution 12, wherein the default value depends on profiles and/or levels.

15. The method of solution 1, wherein the rule further specifies that signaling of the syntax element is conditioned on profiles and/or levels.

16. The method of solution 15, wherein the rule further specifies to infer a value of the syntax element to be a default value, in case that the syntax element is not present.

17. The method of solution 15, wherein the default value is 0 or 1.

18. The method of solution 1, wherein the syntax element is u(1) coded.

19. The method of any of solutions 1 to 18, wherein the conversion includes encoding the video into the bitstream.

20. The method of any of solutions 1 to 18, wherein the conversion includes decoding the video from the bitstream.

21. The method of any of solutions 1 to 18, wherein the conversion includes generating the bitstream from the video, and the method further comprises: storing the bitstream in a non-transitory computer-readable recording medium.

22. A video processing apparatus comprising a processor configured to implement a method recited in any one or more of solutions 1 to 21.

23. A method of storing a bitstream of a video, comprising, a method recited in any one of solutions 1 to 21, and further including storing the bitstream to a non-transitory computer-readable recording medium.

24. A computer readable medium storing program code that, when executed, causes a processor to implement a method recited in any one or more of solutions 1 to 21.

25. A computer readable medium that stores a bitstream generated according to any of the above described methods.

26. A video processing apparatus for storing a bitstream representation, wherein the video processing apparatus is configured to implement a method recited in any one or more of solutions 1 to 21.

A third set of solutions show example embodiments of techniques discussed in the previous section (e.g., items 14b and 14c).

1. A method of video processing (e.g., method 800 as shown in FIG. 8A), comprising: performing 802 a conversion between a video and a bitstream of the video according to a rule, wherein a syntax structure includes information of one or more video coding layers that are included in the bitstream and correspond to one or more output layer sets; and wherein the rule specifies that a starting position of a syntax element in the syntax structure that specifies a level information to which the one or more output layer sets conform is constrained to align to a byte boundary.

2. The method of solution 1, wherein the syntax structure further specifies at least one of profile, tier, sub-profile, and general constraints information to which the one or more output layer sets conform.

3. The method of solution 1, wherein the syntax structure is a profile, tier, level information syntax structure.

4. The method of any of solutions 1-3, wherein the one or more output layer sets are specified by a video parameter set in case that the profile, tier, level information syntax structure is included in the video parameter set.

5. The method of solution 1, wherein the one or more output layer sets refer to an output layer set that includes only a layer that is a lowest layer among layers that refer to a sequence parameter set in case that a profile, tier, level information syntax structure is included in the sequence parameter set.

6. The method of any of solutions 1-5, wherein the rule specifies that the starting position of the syntax element is required to be at a byte boundary.

7. The method of any of solutions 1-5, wherein the rule specifies to add one or more alignment syntax elements to make the starting position of the syntax element to be aligned to the byte boundary.

8. The method of solution 7, wherein the one or more alignment syntax elements are signalled before the syntax element.

9. The method of solution 7, wherein each of the one or more alignment syntax elements is coded with a fixed pattern bit string using one bit.

10. A method of video processing (e.g., method 810 as shown in FIG. 8B), comprising: performing 812 a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that a syntax structure indicates constraint information about the bitstream; wherein the rule specifies that the syntax structure is allowed to include a syntax element without aligning to a byte boundary.

11. The method of solution 10, wherein the rule specifies that the syntax element is included in the syntax structure without being checked whether the syntax element is aligned to the byte boundary or not.

12. The method of solution 10 or 11, wherein the syntax structure comprises a constraint flag.

13. The method of any of solutions 1 to 12, wherein the conversion includes encoding the video into the bitstream.

14. The method of any of solutions 1 to 12, wherein the conversion includes decoding the video from the bitstream.

15. The method of any of solutions 1 to 12, wherein the conversion includes generating the bitstream from the video, and the method further comprises: storing the bitstream in a non-transitory computer-readable recording medium.

16. A video processing apparatus comprising a processor configured to implement a method recited in any one or more of solutions 1 to 15.

17. A method of storing a bitstream of a video, comprising, a method recited in any one of solutions 1 to 15, and further including storing the bitstream to a non-transitory computer-readable recording medium.

18. A computer readable medium storing program code that, when executed, causes a processor to implement a method recited in any one or more of solutions 1 to 15.

19. A computer readable medium that stores a coded representation or a bitstream representation generated according to any of the above described methods.

20. A video processing apparatus for storing a bitstream representation, wherein the video processing apparatus is configured to implement a method recited in any one or more of solutions 1 to 15.

A fourth set of solutions show example embodiments of techniques discussed in the previous section (e.g., items 14d, 15 and 16).

1. A method of video processing (e.g., method 900 as shown in FIG. 9A), comprising: performing 902 a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies where and how reserved bits are included in a syntax structure that indicates one or more coding constraints applicable to the conversion.

2. The method of solution 1, wherein the syntax structure is a general constraints information syntax structure.

3. The method of solution 1 or 2, wherein the rule further specifies to include a first syntax element indicative of a number of the reserved bits in the syntax structure.

4. The method of solution 3, wherein the first syntax element is coded with unsigned integer using N bits, wherein N is an integer.

5. The method of solution 4, wherein N is 8 or 11.

6. The method of solution 1, wherein the first syntax element of the reserved bit is coded with unsigned integer using 0-th order Exp-Golomb-code.

7. The method of solution 3, wherein a reserved general constraints information syntax element is included in the syntax structure.

8. The method of solution 7, wherein the reserved general constraints information syntax element is gci_reserved_zero_bit[i], wherein i ranges from 0 to a value of the first syntax element minus1.

9. The method of solution 1, wherein a first reserved bit and a last reserved bit are at a byte boundary.

10. A method of video processing (e.g., method 910 as shown in FIG. 9B), comprising: determining 912, for a conversion between a video comprising one or more pictures comprising one or more slices and a bitstream of the video, that only I slices are enabled for the conversion according to a rule; and performing 914 the conversion according to the determining, wherein the mile specifies that, responsive to only I slices being enabled, the bitstream conforms to one or more additional constraints.

11. The method of solution 10, wherein the one or more additional constraints constrain syntax elements related to a reference picture list to a certain value that specifies not to use the reference picture list.

12. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to a long term reference picture to a certain value that specifies not to allow the long term reference picture.

13. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to a reference picture list to a certain value that specifies not to allow the reference picture list for an instantaneous decoding refresh (IDR) picture.

14. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to a number of reference picture lists to a certain value that specifies the number of reference picture lists is 0.

15. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to use of an inter-layer prediction to a certain value that specifies all layers are coded independently.

16. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to an applicability of reference picture resampling to a certain value that specifies to disable the reference picture resampling.

17. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to an applicability of resolution change to a certain value that specifies to disable the resolution change.

18. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to an applicability of a weighted prediction for P slices and/or B slices to a certain value that specifies to disable the weighted prediction for P slices and/or B slices.

19. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to an applicability of a sub-block transform to a certain value that specifies to disable the sub-block transform.

20. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to an applicability of a gradual decoding refresh to a certain value that specifies to disable the gradual decoding refresh.

21. The method of solution 10, wherein the one or more additional constraints constrain a syntax element related to an applicability of a coding tool for an inter picture to a certain value that specifies to disable the coding tool.

22. The method of solution 21, wherein the coding tool includes a reference wraparound, temporal motion vector prediction, subblock-based temporal motion vector prediction, adaptive motion vector resolution, bi-directional optical flow, decoder-side motion vector refinement, affine, merge with motion vector difference, symmetric motion vector difference, prediction refinement with optical flow, bi-prediction with coding unit-level weights, combined inter-intra prediction, or geometric partitioning mode.

23. The method of solution 10, wherein the constraint that allows only the I slice type is indicated by a syntax element that specifies whether to impose the constraint.

24. The method of solution 23, wherein the syntax element further specifies that, for each coded slice NAL (network abstraction layer) unit, a NUH (NAL unit header) layer type is IDR_N_LP.

25. A method of video processing (e.g., method 920 as shown in FIG. 9C), comprising: performing 922 a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that one or more syntax elements in a sequence parameter set, a picture parameter set, a picture header, or a sequence header are constrained according to a general constraint information syntax element that indicates a constraint applicable to the conversion.

26. The method of solution 25, wherein the general constraint information syntax element specifies whether each picture contains only a single tile or not.

27. The method of solution 26, wherein the rule specifies, responsive to the general constraint information syntax element specifying that each picture contains only a single tile, to constrain a syntax element indicative of a number of tile columns to specify that the number of tile columns is required to be 1.

28. The method of solution 26, wherein the rule specifies, responsive to the general constraint information syntax element specifying that each picture contains only a single tile, to constrain a syntax element indicative of a number of tile rows to specify that the number of tile rows is required to be 1.

29. The method of solution 26, wherein the rule specifies, responsive to the general constraint information syntax element specifying that each picture contains only a single tile, to constrain a syntax element indicative of a slice partition mode to specify that a rectangular slice mode is in use for each picture referring to a picture parameter set.

30. The method of solution 25, wherein the general constraint information syntax element specifies whether no network abstraction layer (NAL) unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present.

31. The method of solution 30, wherein the general constraint information element constrains a syntax element indicative of an applicability of cross-component adaptive loop filtering to the conversion.

32. The method of solution 31, wherein the rule specifies, responsive to the general constraint information syntax element specifying no NAL unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, to constrain the syntax element such that the cross-component adaptive loop filtering is disabled.

33. The method of solution 31, wherein the rule specifies, responsive to the general constraint information syntax element, no_aps_constraint_flag, equal to 1, to constrain a value of the syntax element, sps_ccalf_enabled_flag is to be equal to 0.

34. The method of solution 30, wherein the general constraint information element constrains the one or more syntax elements indicative of a number of adaptive loop filtering (ALF) luma adaptive parameter sets (APS).

35. The method of solution 34, wherein the rule specifies, responsive to the general constraint information syntax element specifying no NAL unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, to constrain the one or more syntax elements such that the number of ALF APSs that slices in a current picture refer to is 0.

36. The method of solution 34, wherein the rule specifies, responsive to the general constraint information syntax element, no_aps_constraint_flag, equal to 1, to constrain a value of the one or more syntax elements, ph_num_alf_aps_ids_luma and slice_num_alf_aps_ids_luma is to equal to 0.

37. The method of solution 30, wherein the general constraint information element constrains the one or more syntax elements indicative of an applicability of chroma adaptive loop filtering.

38. The method of solution 37, wherein the rule specifies, responsive to the general constraint information syntax element specifying no NAL unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, to constrain the one or more syntax elements such that the chroma adaptive loop filtering is disabled and not applied to Cb and Cr colour components for a current picture.

39. The method of solution 37, wherein the rule specifies, responsive to the general constraint information syntax element, no_aps_constraint_flag, equal to 1, to constrain a value of the one or more syntax elements, ph_alf_cb_flag, ph_alf_cr_flag, sh_alf_cb_flag, and sh_alf_cr_flag, to be equal to 0.

40. The method of solution 25, wherein the rule specifies, responsive to the general constraint information syntax element specifying that each picture contains only a single slice, to constrain a syntax element indicative of a slice partition mode to specify that a rectangular slice mode is in use for each picture referring to a picture parameter set.

41. The method of solution 25, wherein the rule specifies, responsive to the general constraint information syntax element specifying that each picture contains only a single tile and that each picture contains only a single slice, to constrain a syntax element indicative of a picture partition mode to specify that there is no picture partition.

42. The method of solution 25, wherein the rule specifies, responsive to the general constraint information syntax element specifying that each picture contains only a single slice and that the single slice is a rectangular slice, to constrain a syntax element indicative of a number of slices in a picture to specify that the number of slices in the picture is equal to 1.

43. The method of solution 25, wherein the rule specifies, responsive to the general constraint information syntax element specifying that each picture contains only a single subpicture, to constrain a syntax element indicative of a number of subpictures in a picture to specify that the number of subpictures in the picture is equal to 1.

44. A method of video processing (e.g., method 930 as shown in FIG. 9D), comprising: performing 932 a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that whether or how a first syntax element in a syntax structure that indicates one or more constraints applicable to the conversion is indicated is dependent on whether or how a second syntax element is indicated in the syntax structure.

45. The method of solution 44, wherein the rule specifies that responsive to the second syntax element indicating that all the layers are coded independently, the first syntax element indicative of use of an inter-layer prediction in decoding of pictures that refer to a sequence parameter set is constrained to be equal to a value specifying no use of the inter-layer prediction.

46. The method of solution 44, wherein the rule specifies that responsive to the second syntax element indicating that no transform skip is available, the first syntax element indicative of enablement of block differential pulse coded modulation is constrained to be equal to a value specifying disablement of the block differential pulse coded modulation.

47. The method of solution 44, wherein the rule specifies that responsive to the second syntax element indicating no constraint on use of a luma mapping with chroma scaling, a explicit scaling list, or a cross component adaptive loop filtering, the first syntax element is constraint to be equal to a value specifying no constraint on non-presence of network abstraction unit (NAL) of NAL unit type equal to APS_NUT.

48. A method of video processing (e.g., method 940 as shown in FIG. 9E), comprising: performing 942 a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies whether or how a syntax element indicative of general constraints on the conversion is included in the bitstream depends on a profile and/or a level used for the conversion.

49. The method of solution 48, wherein the rule specifies that a value of the syntax element is constrained by the profile and/or the level.

50. The method of solution 48, wherein the rule specifies that the syntax element is omitted responsive to the profile and/or the level not satisfying the rule.

51. The method of solution 48, wherein the rule specifies that the syntax element, when not present, is inferred to be a particular value.

52. The method of solution 51, wherein the particular value is 0 or 1.

53. The method of solution 51, wherein the particular value is dependent on the profile and/or the level.

54. The method of any of solutions 1 to 53, wherein the conversion includes encoding the video into the bitstream.

55. The method of any of solutions 1 to 53, wherein the conversion includes decoding the video from the bitstream.

56. The method of solutions 1 to 53, wherein the conversion includes generating the bitstream from the video, and the method further comprises: storing the bitstream in a non-transitory computer-readable recording medium.

57. A video processing apparatus comprising a processor configured to implement a method recited in any one or more of solutions 1 to 56.

58. A method of storing a bitstream of a video, comprising, a method recited in any one of solutions 1 to 56, and further including storing the bitstream to a non-transitory computer-readable recording medium.

59. A computer readable medium storing program code that, when executed, causes a processor to implement a method recited in any one or more of solutions 1 to 56.

60. A computer readable medium that stores a coded representation or a bitstream representation generated according to any of the above described methods.

61. A video processing apparatus for storing a bitstream representation, wherein the video processing apparatus is configured to implement a method recited in any one or more of solutions 1 to 56.

In the present document, the term “video processing” may refer to video encoding, video decoding, video compression or video decompression. For example, video compression algorithms may be applied during conversion from pixel representation of a video to a corresponding bitstream representation or vice versa. The bitstream representation of a current video block may, for example, correspond to bits that are either co-located or spread in different places within the bitstream, as is defined by the syntax. For example, a macroblock may be encoded in terms of transformed and coded error residual values and also using bits in headers and other fields in the bitstream. Furthermore, during conversion, a decoder may parse a bitstream with the knowledge that some fields may be present, or absent, based on the determination, as is described in the above solutions. Similarly, an encoder may determine that certain syntax fields are or are not to be included and generate the coded representation accordingly by including or excluding the syntax fields from the coded representation.

The disclosed and other solutions, examples, embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.

A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

The processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

While this patent document contains many specifics, these should not be construed as limitations on the scope of any subject matter or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular techniques. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document. 

1. A method of video processing, comprising: performing a conversion between a video and a bitstream of the video according to a rule, and wherein the rule specifies that a first syntax element is included in a profile, tier, level information syntax structure when a value of a profile tier present flag is equal to one, which indicates that profile, tier, and general constraints information is allowed to be present, and wherein a value of the first syntax element indicates whether one or more general constraint information syntax elements are included in a general constraint information syntax structure, and wherein when the value of the first syntax element is equal to zero, the one or more general constraint information syntax elements are not included in the general constraint information syntax structure, and the general constraint information syntax structure does not impose any constraint.
 2. The method of claim 1, wherein the first syntax element is coded with unsigned integer using N bits, wherein N is equal to
 1. 3. The method of claim 1, wherein a second syntax element specifying a level information to which one or more output layer sets conform is included in the profile, tier, level information syntax structure; and wherein the rule specifies that a starting position of the second syntax element in the profile, tier, level information syntax structure is constrained to align to a byte boundary.
 4. The method of claim 1, wherein the rule specifies a third syntax element indicative of a number of reserved bits in the general constraint information syntax structure is included in the general constraint information syntax structure.
 5. The method of claim 4, wherein the third syntax element is coded with unsigned integer using M bits, wherein M is an integer.
 6. The method of claim 4, wherein a reserved general constraints information syntax element is included in the general constraint information syntax structure, and wherein the reserved general constraints information syntax element is gci_reserved_zero_bit[i], wherein i ranges from 0 to a value of the third syntax element minus
 1. 7. The method of claim 6, wherein the reserved general constraints information syntax element is coded with unsigned integer using S bits, wherein S is equal to
 1. 8. The method of claim 1, wherein the rule specifies that one or more syntax elements in a sequence parameter set, a picture parameter set, a picture header, or a slice header are constrained according to a fourth syntax element included in the general constraint information syntax structure, and wherein the fourth syntax element specifies whether no network abstraction layer (NAL) unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, and wherein when a value of the fourth syntax element is equal to 1 and specifies that no NAL unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, a value of a fifth syntax element in the sequence parameter set is constrained to be equal to 0, which specifies that a cross-component adaptive loop filter is disabled, a value of a sixth syntax element in the picture header is constrained to be equal to 0, which specifies that a number of adaptive loop filter (ALF) adaptive parameter sets (APSs) that a picture refers to is equal to 0, a value of a seventh syntax element in the slice header is constrained to be equal to 0, which specifies that a number of ALF APS that a slice refers to is equal to 0, a value of an eighth syntax element in the picture header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cb colour component of a picture, a value of a ninth syntax element in the picture header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cr colour component of a picture, a value of a tenth syntax element in the slice header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cb colour component of a slice, a value of an eleventh syntax element in the slice header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cr colour component of a slice.
 9. The method of claim 1, wherein the conversion includes encoding the video into the bitstream.
 10. The method of claim 1, wherein the conversion includes decoding the video from the bitstream.
 11. An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to: perform a conversion between a video and a bitstream of the video according to a rule, and wherein the rule specifies that a first syntax element is included in a profile, tier, level information syntax structure when a value of a profile tier present flag is equal to one, which indicates that profile, tier, and general constraints information is allowed to be present, and wherein a value of the first syntax element indicates whether one or more general constraint information syntax elements are included in a general constraint information syntax structure, and wherein when the value of the first syntax element is equal to zero, the one or more general constraint information syntax elements are not included in the general constraint information syntax structure, and the general constraint information syntax structure does not impose any constraint.
 12. The apparatus of claim 11, wherein the first syntax element is coded with unsigned integer using N bits, wherein N is equal to
 1. 13. The apparatus of claim 11, wherein a second syntax element specifying a level information to which one or more output layer sets conform is included in the profile, tier, level information syntax structure; and wherein the rule specifies that a starting position of the second syntax element in the profile, tier, level information syntax structure is constrained to align to a byte boundary.
 14. The apparatus of claim 11, wherein the rule specifies a third syntax element indicative of a number of reserved bits in the general constraint information syntax structure is included in the general constraint information syntax structure.
 15. The apparatus of claim 14, wherein the third syntax element is coded with unsigned integer using M bits, wherein M is an integer, wherein a reserved general constraints information syntax element is included in the general constraint information syntax structure, wherein the reserved general constraints information syntax element is gci_reserved_zero_bit[i], wherein i ranges from 0 to a value of the third syntax element minus 1, and wherein the reserved general constraints information syntax element is coded with unsigned integer using S bits, wherein S is equal to
 1. 16. The apparatus of claim 11, wherein the rule specifies that one or more syntax elements in a sequence parameter set, a picture parameter set, a picture header, or a slice header are constrained according to a fourth syntax element included in the general constraint information syntax structure, and wherein the fourth syntax element specifies whether no network abstraction layer (NAL) unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, and wherein when a value of the fourth syntax element is equal to 1 and specifies that no NAL unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, a value of a fifth syntax element in the sequence parameter set is constrained to be equal to 0, which specifies that a cross-component adaptive loop filter is disabled, a value of a sixth syntax element in the picture header is constrained to be equal to 0, which specifies that a number of adaptive loop filter (ALF) adaptive parameter sets (APSs) that a picture refers to is equal to 0, a value of a seventh syntax element in the slice header is constrained to be equal to 0, which specifies that a number of ALF APS that a slice refers to is equal to 0, a value of an eighth syntax element in the picture header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cb colour component of a picture, a value of a ninth syntax element in the picture header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cr colour component of a picture, a value of a tenth syntax element in the slice header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cb colour component of a slice, a value of an eleventh syntax element in the slice header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cr colour component of a slice.
 17. A non-transitory computer-readable storage medium storing instructions that cause a processor to: perform a conversion between a video and a bitstream of the video according to a rule, and wherein the rule specifies that a first syntax element is included in a profile, tier, level information syntax structure when a value of a profile tier present flag is equal to one, which indicates that profile, tier, and general constraints information is allowed to be present, and wherein a value of the first syntax element indicates whether one or more general constraint information syntax elements are included in a general constraint information syntax structure, and wherein when the value of the first syntax element is equal to zero, the one or more general constraint information syntax elements are not included in the general constraint information syntax structure, and the general constraint information syntax structure does not impose any constraint.
 18. The non-transitory computer-readable storage medium of claim 17, wherein the first syntax element is coded with unsigned integer using N bits, wherein N is equal to 1, wherein a second syntax element specifying a level information to which one or more output layer sets conform is included in the profile, tier, level information syntax structure; wherein the rule specifies that a starting position of the second syntax element in the profile, tier, level information syntax structure is constrained to align to a byte boundary, wherein the rule specifies a third syntax element indicative of a number of reserved bits in the general constraint information syntax structure is included in the general constraint information syntax structure, wherein the third syntax element is coded with unsigned integer using M bits, wherein M is an integer, wherein a reserved general constraints information syntax element is included in the general constraint information syntax structure, wherein the reserved general constraints information syntax element is gci_reserved_zero_bit[i], wherein i ranges from 0 to a value of the third syntax element minus 1, wherein the reserved general constraints information syntax element is coded with unsigned integer using S bits, wherein S is equal to 1, wherein the rule specifies that one or more syntax elements in a sequence parameter set, a picture parameter set, a picture header, or a slice header are constrained according to a fourth syntax element included in the general constraint information syntax structure, and wherein the fourth syntax element specifies whether no network abstraction layer (NAL) unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, and wherein when a value of the fourth syntax element is equal to 1 and specifies that no NAL unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, a value of a fifth syntax element in the sequence parameter set is constrained to be equal to 0, which specifies that a cross-component adaptive loop filter is disabled, a value of a sixth syntax element in the picture header is constrained to be equal to 0, which specifies that a number of adaptive loop filter (ALF) adaptive parameter sets (APSs) that a picture refers to is equal to 0, a value of a seventh syntax element in the slice header is constrained to be equal to 0, which specifies that a number of ALF APS that a slice refers to is equal to 0, a value of an eighth syntax element in the picture header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cb colour component of a picture, a value of a ninth syntax element in the picture header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cr colour component of a picture, a value of a tenth syntax element in the slice header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cb colour component of a slice, a value of an eleventh syntax element in the slice header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cr colour component of a slice.
 19. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: generating the bitstream of the video according to a rule, and wherein the rule specifies that a first syntax element is included in a profile, tier, level information syntax structure when a value of a profile tier present flag is equal to one, which indicates that profile, tier, and general constraints information is allowed to be present, and wherein a value of the first syntax element indicates whether one or more general constraint information syntax elements are included in a general constraint information syntax structure, and wherein when the value of the first syntax element is equal to zero, the one or more general constraint information syntax elements are not included in the general constraint information syntax structure, and the general constraint information syntax structure does not impose any constraint.
 20. The non-transitory computer-readable recording medium of claim 19, wherein the first syntax element is coded with unsigned integer using N bits, wherein N is equal to 1, wherein a second syntax element specifying a level information to which one or more output layer sets conform is included in the profile, tier, level information syntax structure; wherein the rule specifies that a starting position of the second syntax element in the profile, tier, level information syntax structure is constrained to align to a byte boundary, wherein the rule specifies a third syntax element indicative of a number of reserved bits in the general constraint information syntax structure is included in the general constraint information syntax structure, wherein the third syntax element is coded with unsigned integer using M bits, wherein M is an integer, wherein a reserved general constraints information syntax element is included in the general constraint information syntax structure, wherein the reserved general constraints information syntax element is gci_reserved_zero_bit[i], wherein i ranges from 0 to a value of the third syntax element minus 1, wherein the reserved general constraints information syntax element is coded with unsigned integer using S bits, wherein S is equal to 1, wherein the rule specifies that one or more syntax elements in a sequence parameter set, a picture parameter set, a picture header, or a slice header are constrained according to a fourth syntax element included in the general constraint information syntax structure, and wherein the fourth syntax element specifies whether no network abstraction layer (NAL) unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, and wherein when a value of the fourth syntax element is equal to 1 and specifies that no NAL unit with NAL unit type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT is present, a value of a fifth syntax element in the sequence parameter set is constrained to be equal to 0, which specifies that a cross-component adaptive loop filter is disabled, a value of a sixth syntax element in the picture header is constrained to be equal to 0, which specifies that a number of adaptive loop filter (ALF) adaptive parameter sets (APSs) that a picture refers to is equal to 0, a value of a seventh syntax element in the slice header is constrained to be equal to 0, which specifies that a number of ALF APS that a slice refers to is equal to 0, a value of an eighth syntax element in the picture header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cb colour component of a picture, a value of a ninth syntax element in the picture header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cr colour component of a picture, a value of a tenth syntax element in the slice header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cb colour component of a slice, a value of an eleventh syntax element in the slice header is constrained to be equal to 0, which specifies that the adaptive loop filter is disabled for a Cr colour component of a slice. 